The Characteristics and Clinical Outcomes of Rotational Atherectomy under Intra-Aortic Balloon Counterpulsation Assistance for Complex and Very High-Risk Coronary Interventions in Contemporary Practice: An Eight-Year Experience from a Tertiary Center

Abstract

Background

The use of Complex and High-risk Coronary Interventions (CHIPs) has increased in recent years. Both rotational atherectomy (RA) and hemodynamic support are important parts of CHIPs.

Objectives

This study aimed to retrospectively investigate the procedure results and clinical outcomes of intra-aortic balloon pump (IABP)-assisted RA in the contemporary drug-eluting stent era.

Methods

All consecutive patients who received RA under in-procedure IABP assistance from April 2010 to March 2018 were analyzed retrospectively.

Results

A total of 63 patients (77.7 ± 10.1 years, 69.8% male) were recruited, of whom 51 underwent RA with primary IABP assistance and 12 underwent bailout IABP. RA could be completed in 61 (96.8%) of the patients. Overall, vessel perforation, profound in-procedure shock, and ventricular arrhythmia occurred in 1.6%, 4.8% and 3.2% of the patients, respectively. The in-hospital, 30-day and 90-day major adverse cardiac event (MACE) rates were 22.2%, 27.4% and 36.1%, respectively, mostly driven by mortality. The MACE rates were significantly higher in the bail-out group in the hospital (50.0% vs. 15.7%, p = 0.018) at 30 days (58.3% vs. 20.0%, p = 0.013) and 90 days (66.7% vs. 28.6%, p = 0.020).

Conclusions

Bail-out IABP was associated with increased MACEs, implying that the use of IABP should be implemented at the beginning of RA if a complex procedure is anticipated.

INTRODUCTION

Severe coronary calcifications are associated with significantly worse outcomes after percutaneous coronary interventions even in the drug-eluting stent (DES) era.^1,2 Rotational atherectomy (RA) is considered to be the standard treatment for heavily calcified coronary lesions, including unprotected left main,^3,4 bifurcation,^5,6 long^7,8 and chronic total occlusive (CTO) lesions,^9,10 even in an acute coronary syndrome setting^11,12 and among the elderly.¹³ In the bare-metal stent era, RA was mostly used for debulking and plaque removal, especially in bifurcation lesions with huge plaque burden.¹⁴ Only in the DES era has RA been used for compliance modifications of calcified lesions so that the vessels can be opened and fully treated.^15,16 Currently, RA is performed primarily for lesions with severe circular or rotating intimal calcifications or as bail-out procedure in cases of device-uncrossable or undilatable lesions.¹⁷ In recent years, Complex and High-risk Coronary Interventions (CHIPs) have drawn a lot of attention, because most patients derive large benefits from revascularization.¹⁸ However, bypass surgery may not be suitable because of multiple risk factors and prohibitive co-morbidities, including advanced age, severely impaired cardiac, respiratory or renal function and frailty.^19,20 Given these clinical scenarios, complex coronary anatomy with high SYNTAX score and severe coronary calcifications are commonly seen, so that RA is frequently used as primary or secondary treatment in these patients.

For patients with severe existing left ventricular dysfunction or those expected to have major left ventricular dysfunction during the procedure such as percutaneous coronary intervention (PCI) for last-remaining vessels or unilateral vessels when contra-lateral vessels are occluded or severely compromised, left ventricular hemodynamic support during the procedure is usually needed.²¹ This can be achieved with intra-aortic balloon counterpulsation (IABP), extracorporeal membrane oxygenator (ECMO), or with a left-ventricular assistant device. However, IABP is more popular and available in real-world practice.²² As RA is expected to be more technically challenging and is associated with transient or longer-lasting systemic hypotension or even cardiogenic shock, hemodynamic-supported RA is not unusual in CHIPs. However, few studies have reported IABP-assisted RA in the literature, and most of them were conducted early after RA was introduced and in the bare-metal stent (BMS) era, when coronary complexities were not that high and calcifications not that advanced.²³ Moreover, similar studies in modern practice in the DES era are lacking, and advances in PCI devices, techniques, skill and experience may have an impact on procedural and clinical outcomes. Therefore, the current study was carried to retrospectively evaluate the clinical circumstances, procedure results and clinical outcomes of IABP-assisted RA in CHIPs in the DES era at a single high-volume institute.

METHODS

Patient population

A Windows-based database containing all consecutive cardiac catheterization report data stored in the hospital’s information system running on a mainframe computer was established in 1993 and has been well maintained ever since. In order to recruit patients for this study, all patients who received RA therapy for coronary lesions under in-procedure IABP assistance from April 2010 to March 2018 were identified in the database and screened manually. Patients who underwent RA plus IABP with the concomitant use of ECMO, TandemHeart^® (CardiacAssist, Inc., Pittsburgh, PA, US) or Impella^® (Abiomed, Danvers, MA, US) were excluded. The timing of setting up IABP was at the discretion of the interventional operators and could be either primary if IABP was inserted and pumping before PCI, or bailout if IABP was set up on demand during or after PCI. The latter indication for IABP was hypotension during the procedure and could be secondary to any complication.

The indications, procedure details and complications at the time of the index PCI were retrieved from the aforementioned cardiac catheterization report database. The computerized electronic medical chart records of each patient were reviewed in detail, and relevant clinical information and biochemical findings at the time of hospitalization and during follow-up were retrieved and recorded in a case record form. If the patients had missed clinical follow-up for more than three months before the time of this study, they or their family members were contacted by telephone. In cases of patient mortality, the cause of death as stated in the death certificate was retrieved and confirmed. In this study, the definition of shock was systolic blood pressure lower than 90 mmHg after appropriate fluid supplement together with clinical or laboratory evidence of hypoperfusion. Those who remained in a similar or worse status despite high-dose vasopressor support greater than 0.5 μg/kg/min of norepinephrine or equivalent were defied as being in "profound/refractory shock". The study design and protocol were approved by the Institutional Review Board for Human Research in our institute.

Angiographic characterization and measurements

Each angiogram was viewed and analyzed on a workstation equipped with special software for the quantitative analysis of angiograms (Rubo DICOM Viewer, version 2.0, build 170828, Rubo Medical Imaging, Aerdenhout, The Netherlands). Angiographic characteristics of target lesions in the index coronary angiogram were measured by meticulously evaluating the session cine. The SYNTAX scores before and after PCI were calculated using the standard calculator software available on the official website. The number of vessels involved in coronary artery disease was defined as the number of the three major coronary vessels with stenosis ≥ 70% in diameter by quantitative coronary analysis (QCA). Severe coronary artery calcification was defined as apparent abluminal radio-opacity on two sides of the vascular walls that appeared in two different projections on the cine without cardiac movement and before the injection of contrast medium.

All PCIs were performed by certified interventional cardiologists in accordance with the standard practice at our cath lab. Patients were pretreated with a standard dose of aspirin and clopidogrel (or ticagrelor). Calcium channel blockers and nitrates were also used to prevent coronary artery spasm. Heparin was administered to maintain an activated clotting time (ACT) of ≥ 300 seconds during the procedure. The decision to perform RA was guided by standard practice but also at the discretion of the operator. The indications for RA were primary (for heavy and circular/rotating intimal calcification) or secondary as a bail-out procedure (for undilatable or uncrossable lesions). For patients with the primary use of IABP, it was set up via the femoral artery using standard techniques immediately before initiation of PCI and confirmed to work properly. Prior to RA, a 0.009-inch floppy RotaWire^TM was advanced through the lesion using the wire-exchange technique. A bolus of 1,200-1,600 ug of isosorbide dinitrate was given intracoronarily prior to the start of RA, during which normal saline mixed with heparin and isosorbide dinitrate was slowly infused. RA was implemented using the Rotablator^TM RA system, starting with a 1.25 or 1.5 mm burr at a speed of 180,000-200,000 rpm, and this was often supplemented with another burr one size bigger. The advance time of each burr was less than 30 seconds. For patients who needed side branch (SB) RA, the sequence of RA for the SB or main vessel (MV) was determined according to which vessel was more critically diseased and potentially jeopardized if not treated first, and also at the discretion of the operator. After the vessel and blood flow in the first treated vessel were secured, rotawiring of another vessel was performed, followed by RA of the second vessel. After accomplishing RA, a workhorse wire replaced the RotaWire^TM using the same wire exchange technique and the procedure proceeded with balloon angioplasty with or without stent implantation to achieve optimal angiographic results and minimal residual stenosis. For patients with bail-out IABP, it was set up in case of hemodynamic instability in the middle of the procedure, also using standard techniques via femoral access and confirmed to pump properly. Whenever indicated, glycoprotein IIb/IIIa inhibitors and/or inotropics were administered. Completion of RA was defined as full debulking of the target lesion without premature termination of RA before proceeding to subsequent treatment. After stent implantation, dual antiplatelet therapy with aspirin (100 mg/day) and clopidogrel (75 mg/day; or ticagrelor 90 mg twice day) were continued for at least 12 months after DES implantation.

Clinical outcomes

Major adverse cardiac events (MACE)s at follow-up were defined as all-cause death, stroke, non-fatal myocardial infarction or target vessel revascularization. In addition, cardiovascular major adverse cardiac events (CV MACEs) were defined as cardiovascular death, stroke, non-fatal myocardial infarction or target vessel revascularization.

Statistical analysis

Data of continuous variables were expressed as mean ± SEM, and categorical variables were expressed as number and frequency. Intergroup differences in means were assessed using unpaired Student’s t-tests, and differences in categorical variables were assessed using the chi-square test with Yate’s correction. Kaplan-Meier curves were plotted to estimate the cumulative incidence of MACEs over 90 days. The log-rank test was used for comparisons between the two groups. Multivariable logistic regression analysis was performed to identify any independent predictors for in-hospital mortality. Variables witha p-value < 0.20 in univariable analysis were entered into the multivariable model. All statistical analyses were performed using IBM SPSS statistical software for Windows, version 24.0.0.0 (IBM Corp., New York, US). Two-tailed p-values < 0.05 were considered to be statistically significant.

RESULTS

Baseline characteristics of the patients

During the study period, a total of 8036 PCI and 382 rotablations were performed at the cath labs. One patient underwent rotablation with ECMO support and three other patients underwent rotablation with concomitant IABP and ECMO support. Among them, two presented with out-of-hospital cardiac arrest and all had hemodynamic instability on initial presentation. These four patients were excluded from the study. A total of 63 patients (44 males and 19 females; mean age 77.7 ± 10.1 years) were recruited into this study (Table 1). The rate of IABP usage among the PCI patients was 4.75%, and that of IABP backup in rotablation subjects was 16.5%. Most of the patients presented with high-risk profiles (acute coronary syndrome 76.1%, ischemic cardiomyopathy 15.9%, and shock in 33.4%) with stable angina presenting only in 7.9% of the patients. Hypertension was present in 52.4%, diabetes in 52.4% and peripheral arterial disease in 17.5% of the patients. The baseline left ventricular ejection fraction (LVEF) was only 37.2 ± 12.4%, and the serum creatinine level was 2.6 ± 2.5 mg/dl. Multiple coronary vessel disease was present in 95.2% of the patients, and left main lesions in 38.1%. Previous coronary artery bypass grafting (CABG) was noted in 12.7% of the patients. These clinical presentations were consistent with very high-risk profiles. Among them, 51 patients (80.9%, mean age 77.5 ± 10.3 years, 35 males and 16 females) underwent rotational atherectomy with primary IABP assistance (primary IABP group) and another 12 patients (19.1%, mean age 78.5 ± 9.7 years, 9 males and 3 females) underwent rotablation with in-procedure bailout IABP (bailout IABP group). These two groups had similar demographic characteristics (Table 1) except for a lower level of serum hemoglobin in the primary IABP group (10.8 ± 2.2 g/dl vs. 12.4 ± 2.0 g/dl, p = 0.026).

Table 1. Demographic data of rotational atherectomy with IABP implant before PCI (primary IABP) vs. RA with IABP implant during or after PCI (bailout IABP) cases in the study period.

Variables	Both (N = 63)	Primary IABP (N = 51)	Bailout IABP (N = 12)	p-value*
Sex (M/F)	44/19	35/16	9/3	1.000
Age (years)	77.7 ± 10.1	77.5 ± 10.3	78.5 ± 9.7	0.753
Clinical diagnosis (N, %)				0.114
Stable angina	5 (7.9%)	5 (9.8%)	0
Unstable angina	11 (17.5%)	9 (17.6%)	2 (16.7%)
NSTEMI	16 (25.4%)	14 (27.5%)	2 (16.7%)
STEMI	2 (3.2%)	1 (2.0%)	1 (8.3%)
Ischemic CM	8 (12.7%)	8 (15.7%)	0
Unstable angina + shock	2 (3.2%)	2 (3.9%)	0
NSTEMI + shock	8 (12.7%)	6 (11.8)	2 (16.7%)
STEMI + shock	9 (14.3%)	4 (7.8%)	5 (41.7%)
Ischemic CM + shock	2 (3.2%)	2 (3.9%)	0
Hypertension (N, %)	33 (52.4%)	25 (49.0%)	8 (66.7%)	0.271
Diabetes (N, %)	33 (52.4%)	26 (51.0%)	7 (58.3%)	0.646
PAD (N, %)	11 (17.5%)	6 (11.8%)	3 (25.0%)	0.354
Baseline LVEF (%)	37.2 ± 12.4	38.0 ± 12.2	33.8 ± 13.3	0.341
Lab data
Hemoglobin (g/dl)	11.1 ± 2.2	10.8 ± 2.2	12.4 ± 2.0	0.026
BUN (mg/dl)	43.3 ± 42.9	45.1 ± 48.3	37.8 ± 19.2	0.611
Cr (mg/dl)	2.6 ± 2.5	2.7 ± 2.7	2.1 ± 1.0	0.217
Cholesterol (mg/dl)	140.9 ± 29.2	141.5 ± 29.8	135.5 ± 25.8	0.701
HDL-chol (mg/dl)	44.0 ± 12.3	44.0 ± 12.8	44.3 ± 8.1	0.970
LDL-chol (mg/dl)	81.0 ± 26.5	81.9 ± 26.4	63.0 ± 29.7	0.331
FBS (mg/dl)	176.42 ± 93.6	183.1 ± 87.5	155.3 ± 112.6	0.374
HbA1c (mg/dl)	7.1 ± 2.0	6.9 ± 1.5	8.0 ± 4.3	0.617
Total CK (U/L)	188.0 ± 226.7	194.6 ± 219.3	160.7 ± 247.8	0.692
CK-MB (U/L)	21.4 ± 24.1	21.4 ± 25.9	21.3 ± 17.4	0.990
Troponin (ng/ml)	12.0 ± 18.6	10.5 ± 15.7	17.1 ± 26.3	0.464
CAD vessels				0.122
SVD (N, %)	3 (4.8%)	2 (4.0%)	1 (8.3%)
DVD (N, %)	18 (28.6%)	12 (23.5%)	6 (50.0%)
TVD (N, %)	42 (66.7%)	37 (72.5%)	5 (41.7%)
Plus LM (N, %)	24 (38.1%)	22 (43.1%)	2 (16.7%)	0.110
Prior CABG (N, %)	8 (12.7%)	6 (11.8%)	2 (16.7 %)	0.641

* RA with primary IABP vs. RA with bailout IABP.

ACS, acute coronary syndrome; BUN, blood urea nitrogen; CABG, coronary artery bypass grafting; CAD, coronary heart disease; CK, creatine kinase; CK-MB, creatine Kinase MB; DVD, double vessel disease; F, female; FBS, fasting blood sugar; HbA1c, glycated hemoglobin; HDL-chol, high-density lipoprotein cholesterol; IABP, intra-aortic balloon pump; ischemic CM, ischemic cardiomyopathy; LDL-chol, low-density lipoprotein cholesterol; LVEF, left ventricular ejection fraction; M, male; NSTEMI, non-ST elevation myocardial infarction; PAD, peripheral artery disease; PCI, percutaneous coronary intervention; STEMI, ST-elevation myocardial infarction; SVD, single vessel disease; TVD, triple vessel disease.

PCI procedural characteristics

Rotablation for single vessels accounted for 73% of the procedures, mostly for left anterior descending (LAD) lesions (Table 2), whereas rotablation for double vessel disease accounted for 20.7% of the procedures. Rotablation for isolated left main (LM) or LM in combination with other vessels was done in 25.6% of the cases. Femoral access was more common than radial access (93.7% vs. 6.3%), and 7Fr. sheaths were used more often than 6Fr. sheaths (79.4% vs. 20.6%). The baseline SYNTAX scores were high at up to 38.1 ± 10.6 and the residual scores were 10.0 ± 10.3 with a gain of 28.1 ± 11.2. RA was completed in 61 (96.8%) of the patients. The most used burrs were 1.5 mm or above (85.7%). All of the lesions were heavily calcified, and the RA-treated lesion length was 58.5 ± 26.4 mm. Vessel tortuosity, bifurcation lesions and CTO were seen in 29.0%, 40.3% and 14.5% of the patients, respectively. Type C lesions were the most common (95.2%) in these cases. The final stent size and length were 2.7 ± 0.4 and 61.8 ± 29.2 mm, respectively. The procedure and fluoroscopic times were 191.6 ± 71.5 and 55.9 ± 29.5 minutes, respectively. In terms of primary versus bail-out IABP, more radial approach PCIs (25.0% vs. 2.0%, p = 0.020) were used, but the SYNTAX score gain was lower (30.0 ± 10.9 vs. 20.0 ± 9.0) in the bail-out group, despite similar baseline SYNTAX scores (38.8 ± 10.1 vs. 35.0 ± 1.2, p = 0.263). Furthermore, less ostial and bifurcation lesions were seen in the bail-out IABP group. There were no significant differences in procedure or fluoroscopic times between the two subgroups.

Table 2. Demographic, and PCI findings of rotational atherectomy with IABP implant before PCI (RA with primary IABP) vs. RA with IABP implant during or after PCI (RA with bailout IABP) cases in the study period.

Variables	Both (N = 63)	Primary IABP (N = 51)	Bailout IABP (N = 12)	p-value*
Rotablation vessels				0.059
LM (N, %)	1 (1.6%)	1 (2.0%)	0
LAD (N, %)	38 (60.3%)	32 (62.7%)	6 (50.0%)
LCX (N, %)	1 (1.6%)	0	1 (8.3%)
RCA (N, %)	6 (9.5%)	3 (5.9%)	3 (25.0%)
LM + LAD (N, %)	1 (1.6%)	1 (2.0%)	0
LM + LCX (N, %)	1 (1.6%)	1 (2.0%)	0
LAD + LCX (N, %)	8 (12.7%)	8 (15.7%)	0
LAD + RCA (N, %)	2 (3.2%)	1 (2.0%)	1 (8.3%)
LCX + RCA (N, %)	1 (1.6%)	0	1 (8.3%)
LM + LAD + LCX (N, %)	3 (4.8%)	3 (5.9%)	0
LM + LAD + RCA (N, %)	1 (1.6%)	1 (2.0%)	0
Access site				0.020
Radial (N, %)	4 (6.3%)	1 (2.0%)	3 (25.0%)
Femoral (N, %)	59 (93.7%)	50 (98.0%)	9 (75.0%)
Guide size				1.000
6F (N, %)	13 (20.6%)	11 (21.6%)	2 (16.7%)
7F (N, %)	50 (79.4%)	40 (78.4%)	10 (83.3%)
Syntax score#	38.1 ± 10.6	38.8 ± 10.1	35.0 ± 12.2	0.263
Syntax score post-PCI#	10.0 ± 10.3	8.8 ± 8.9	15.0 ± 14.1	0.169
Syntax score gain#	28.1 ± 11.2	30.0 ± 10.9	20.0 ± 9.0	0.005
Rotablation completed	61 (96.8%)	50 (98.0%)	11 (91.7%)	0.347
Largest burr size				0.058
1.25 mm (N, %)	9 (14.3%)	7 (13.7%)	2 (16.7%)
1.5 mm (N, %)	42 (66.7%)	37 (72.5%)	5 (41.7%)
1.75 mm (N, %)	12 (19.0%)	7 (13.7%)	5 (41.7%)
Stenting (N, %)	59(93.7%)	50 (98.0%)	9 (75.0%)	0.020
BMS (N, %)	11 (18.6%)	7 (14.0%)	4 (44.4%)	0.053
DES (N, %)	48 (81.4%)	43 (86.0%)	5 (55.6%)
Stent size (mm)	2.7 ± 0.4	2.7 ± 0.4	2.8 ± 0.2	0.292
Total stent length (mm)	61.8 ± 29.2	63.2 ± 29.6	54.0 ± 27.2	0.390
Rotablation vessel characteristics†
Total lesion length (mm)	58.5 ± 26.4	59.7 ± 26.9	53.0 ± 24.8	0.447
Heavy calcification	62 (100%)	50 (100%)	12 (100%)	N/A
Tortuosity	18 (29.0%)	15 (30.0%)	3 (25.0%)	1.000
Ostial lesion (N, %)	26 (41.9%)	24 (48.0%)	2 (16.7%)	0.048
Bifurcation (N, %)	25 (40.3%)	24 (48.0%)	1 (8.3%)	0.019
Chronic total occlusion	9 (14.5%)	5 (10.0%)	4 (33.3%)	0.062
ACC/AHA lesion (N, %)				0.482
B2	3 (4.8%)	2 (4.0%)	1 (8.3%)
C	59 (95.2%)	48 (96.0%)	11 (91.7%)
Total procedure time (min)	191.6 ± 71.5	184.8 ± 74.4	220.7 ± 50.0	0.119
Total fluoro time (min)	55.9 ± 29.5	54.5 ± 29.5	61.9 ± 30.1	0.439
Total contrast dose (ml)	195.5 ± 81.4	189.4 ± 61.4	243.5 ± 176.4	0.489

* RA with primary IABP vs. RA with bailout IABP; ^# Residual syntax score in patients with prior CABG; ^† One patient in RA with primary IABP with incomplete angiography DICOM was excluded.

ACC/AHA, American College of Cardiology/American Heart Association; BMS, bare metal stent; CABG, coronary artery bypass grafting; DES, drug-eluting stent; DICOM, Digital Imaging and Communications in Medicine; IABP, intra-aortic balloon pump; LAD, left anterior descending artery; LCX, left circumflex artery; LM, left main coronary artery; PCI, percutaneous coronary intervention; RA, rotational atherectomy; RCA, right coronary artery.

Procedure outcomes

Overall, vessel perforation, wire fracture, profound in-procedure shock, and ventricular arrhythmia occurred in 1.6%, 1.6%, 4.8% and 3.2% of the patients, respectively. Acute contrast-induced nephropathy (CIN) occurred more frequently (27.0%) (Table 3). No patient died during the procedure and no patient needed emergent CABG for the procedure. However, the bail-out IABP group was associated with more in-procedure profound shock (25.0% vs. 0%, p = 0.006).

Table 3. Procedure outcomes of rotational atherectomy with IABP implant before PCI (RA with primary IABP) vs. RA with IABP implant during or after PCI (RA with bailout IABP) cases in the study period.

Variables	Both (N = 63)	Primary IABP (N = 51)	Bailout IABP (N = 12)	p-value*
Acute no flow (N, %)	0	0	0	N/A
Perforation (N, %)	1 (1.6%)	0	1 (8.3%)	0.190
Wire transection (N, %)	1 (1.6%)	1 (2.0%)	0	1.000
Profound/refractory shock	3 (4.8%)	0	3 (25.0%)	0.006
Ventricular arrhythmia (N, %)	2 (3.2%)	1 (2.0%)	1 (8.3%)	0.347
Emergent CABG (N, %)	0	0	0	N/A
Die on table (N, %)	0	0	0	N/A
Acute CIN (N, %)	17 (27.0%)	12 (23.5%)	5 (41.7%)	0.279

* RA with primary IABP vs. RA with bailout IABP.

CIN, contrast-induced nephropathy. Abbreviations are in Table 1.

In-hospital and short-term clinical outcomes

For all patients undergoing IABP-supported RA, the in-hospital, 30-day and 90-day MACE rates were 22.2%, 27.4% and 36.1%, respectively, and the CV MACE rates were 17.5%, 21.0% and 24.6%, respectively. Most of the MACEs and CV MACEs were driven by total deaths and CV deaths. The in-hospital, 30-day and 90-day mortality rates were 22.2%, 27.4% and 34.4%, respectively, and the CV mortality rates were 17.5%, 21.0% and 23.0%, respectively. Regarding the timing of IABP implementation, the MACE rates were significantly higher in the bail-out group in the hospital (50.0% vs. 15.7%, p = 0.018), at 30 days (58.3% vs. 20.0%, p = 0.013) and at 90 days (66.7% vs. 28.6%, p = 0.020). The Kaplan-Meier curve for cumulative incidence of MACEs at 90 days between the RA with primary IABP group and bail-out group is shown in Figure 1. The CV MACE rate at 90 days was also significantly higher in the bail-out group (58.3% vs. 16.3%, p = 0.006). However, there were no significant differences in the 90-day event rates of non-fatal myocardial infarction (2.0% vs. 0%, p = 1.000), target vessel revascularization (2% vs. 8.3%, p = 0.357), stroke (both 0%) or stent thrombosis (2% vs. 8.3%, p = 0.357) between the primary IABP and bail-out IABP groups.

Figure 1.

Kaplan-Meier curve for cumulative incidence of major adverse cardiac event (MACE) at 90 days between rotational atherectomy with intra-aortic balloon pump (IABP) implant before percutaneous coronary intervention (PCI) (rotablation with primary IABP) and rotablation with IABP implant during or after PCI (rotablation with bailout IABP).

Multivariable logistic regression analysis for in-hospital mortality

The multivariable analysis identified that both "initial presentation with shock" and "bail-out IABP" were independent predictors for in-hospital mortality (Table 4). However, this analysis was underpowered due to the limited number of cases, and thus should be interpreted with caution.

Table 4. Multivariable logistic regression analysis to identify independent predictors for in-hospital mortality.

Variables	Univariable			Multivariable
	OR	95% CI	p-value	OR	95% CI	p-value
Age	1.03	0.94-1.13	0.575
Diabetes	0.26	0.04-1.54	0.137	0.24	0.05-1.15	0.074
LVEF < 30%	2.24	0.42-11.86	0.342
Shock	5.71	1.06-30.81	0.043	8.51	1.95-37.11	0.004
Syntax Score	0.98	0.90-1.06	0.581
Bailout IABP	3.50	0.61-20.28	0.162	5.01	1.03-24.41	0.046

Omnibus test: χ² = 12.62, df = 14, p = 0.049. Likelihood ratio test: χ² = 17.82, df = 3, p < 0.001.

CI, confidence interval; IABP, intra-aortic balloon pump; LVEF, left ventricular ejection fraction; OR, odds ratio.

DISCUSSION

In the current study, we found that RA under IABP assistance in the DES era was performed in very old patients with very high clinical risk (ACS, ischemic cardiomyopathy with or without shock, depressed baseline left ventricular (LV) function, diabetes, poor renal function) and complex coronary anatomy (multiple vessel disease, high LM involvement and very high SYNTAX score) with heavy calcification. All RA-treated lesions were heavily calcified, and the treated length as well as the stent length were long. A significant percentage of the patients needed RA to treat more than a single vessel. Given the complexities of these lesions, the residual SYNTAX score remained high despite RA treatment. In spite of the clinical risks and lesion complexities, the in-procedure complication rate was quite acceptable despite a high incidence of profound in-procedure shock, especially in the bail-out IABP group, comparted with stable angina patients reported in the literature. However, the in-hospital, 30-day and 90-day MACE or CV MACE rates remained high and occurred in approximately one fourth of the patients, mostly due to mortality. We also found that bail-out IABP in these complex and high-risk patients was associated with significant increases in in-hospital and short-term MACEs and mortality, implying that the use of IABP should be implemented at the beginning of RA rather than as a bail-out procedure.

The concept of IABP-backed RA is not new, and was first reported in 1995 by O’Murchu et al.²³ Despite similar procedural outcomes, their patients were much younger (72 ± 7 vs. 77.7 ± 10.1 years), had a much lower rate of diabetes (21% vs. 52.4%), fewer type C lesions (14% vs. 95.2%), but much higher LVEF (49 ± 20% vs. 37.2 ± 12.4%) than ours. In addition, heavy calcifications accounted for only 57% of the treated lesions, and the treated lesion length was only 9 ± 6 mm. However, they did find that IABP use was the only predictor for procedures without hypotension. Nevertheless, the use of IABP to assist PCIs in high-risk patients can be complicated by cost, vascular complications²⁴ and may be precluded by a lack of vascular access. Ramana et al.²⁵ reported the use of RA in patients with severe LV dysfunction without IABP assistance, and in their study the procedure was 100% successful without any procedure-related mortality despite a very low LVEF of 21.3%, multiple-vessel disease, and high rates of hypertension and renal insufficiency. However, in their study, the mean patient age was only 65.7 years, only 30.4% of the patients had diabetes, most patients received RA for single vessel disease, heavy calcification accounted for only 74.1% of the lesions, and the average lesion length was only 20 mm. Moreover, 82.6% of the indication for RA was for debulking as in the BMS era rather than for compliance modification. In addition, the average duration of RA run was only 22 seconds. Therefore, the lesion complexity, PCI technical requirement and patient risk profiles were much lower than ours, and this may explain why RA could be done without IABP assistance. Another study also reported that RA could be done in patients with severe LV dysfunction without hemodynamic support.²⁶ Even though RA could be effectively done in their patients, they concluded that their patients were at an increased risk of prolonged procedural hypotension requiring bail-out hemodynamic support, and the prompt implementation of hemodynamic support mitigated any impact of procedure hypotension on in-hospital MACE and mortality rates. However, in their study, very few patients had an LVEF ≤ 30%, and the in-hospital MACE rate was 11.1%. In addition, the age of the patients was much younger than ours (70 ± 12 vs. 77.7 ± 10.1 years). Furthermore, they did not mention lesion characteristics, SYNTAX score, renal function, and other risk profiles. The PROTECT II study was a multicenter, randomized trial to evaluate the effect of Impella^® 2.5 vs. IABP assistance in high-risk PCIs,²⁷ in which Impella^® 2.5 assistance was found to be associated with a lower MACE rate at 90 days, and the subgroup of patients treated with RA had a higher incidence of periprocedural myocardial infarction. In a substudy of PROTECT II, Cohen et al. found that patients treated with RA had more co-morbidities and more complex and extensive coronary artery diseases, and that RA treatment resulted in higher periprocedural myocardial infarction but not mortality.²⁸ RA was also used more aggressively in those with Impella^® assistance and was associated with a higher rate of periprocedural myocardial infarction. The use of prophylactic TandemHeart^® in high-risk PCIs, including RA, has also been reported to be associated with a high success rate.²⁹ However, in real-world practice, IABP is much more available in cath labs, easier to set up, less traumatic to the vessel wall, and costs much less. In places or countries where LV assistant devices are not available as in ours, the use of IABP or ECMO in assisting high-risk PCIs is more reasonable and practical.

Even though some studies have shown that high SYNTAX score LM and multivessel disease are better treated with bypass surgery, as indicated clearly in current PCI guidelines, the choice and final option of the revascularization modality depend on both the coronary anatomy and also the patient’s age, economic status, willingness, associated risk factors, co-morbidities and frailty,¹⁹ some of which will prohibit surgery. These are also the reasons why our very high-risk patients still opted for PCI despite very complex coronary anatomy with high SYNTAX scores, for which surgical bypass would normally have been the better choice. CHIPs have become a hot topic in recent years, and are targeted at these patients. CHIPs demand advanced PCI skills, especially for diffuse, calcified and CTO lesions. Hemodynamic support for patients with severe LV dysfunction is also an important part of CHIPs. Advances in PCI devices, techniques and skill, along with the superior long-term performance of DES and availability of hemodynamic support, all help to overcome the difficulties with CHIP. This is supported by our quite acceptable PCI performance in the current study. However, an advanced patient age, multiple and advanced co-morbidities, pre-procedural organ failure and severe LV dysfunction remain barriers to salvage every patient. Given the very high-risk profiles and advanced age of our patients, we believe that our practice and results reflect what can be achieved with RA under IABP support by experienced operators at a tertiary center in real-world practice. Interestingly, we found that bail-out IABP in these complex and high-risk patients was associated with significantly increased in-hospital and short-term MACE and mortality rates. This is consistent with the fact that RA for long and difficult calcified lesions can induce transient slow flow, hypotension and, sometimes, profound shock. These complications are difficult to handle, and it is hard to sustain the patient. Our findings suggest that the use of IABP should be implemented at the beginning of a PCI rather than done as a bail-out procedure when RA is to be used in CHIPs with severe background LV dysfunction.

Study limitations

There are several limitations to this study. First, the retrospective design is inherently subject to selection bias and other limitations such as confounding factors. However, this study reflects real-world practice when long and heavily-calcified lesions require RA and severe LV dysfunction at baseline or during the procedure requires LV hemodynamic support. These factors usually occur in very high-risk patients with very complex coronary anatomy in whom CABG may be a better choice but is completely excluded by the prohibitive surgical risk or the patients’ willingness. Second, although this study is the largest cohort to date on RA of complex calcified lesions under IABP assistance in the modern era, the number of patients was still limited. In fact, these patients were very high-risk, with an advanced age, multiple risk factors, multiple co-morbidities, LV dysfunction, and very complex coronary anatomy with high SYNTAX scores. Even though they were not suitable for bypass surgery, a PCI operator who lacked experience with the techniques and RA would be reluctant to treat these patients. However, it is interesting to examine the treatment outcomes in this particular patient group to see what can be improved. Surprisingly, we found that the procedure outcomes were quite acceptable, but that the use of bail-out IABP was associated with dramatically worse outcomes. Therefore, prophylactic IABP should be used in these patients. This small study was under-powered to conduct multivariate logistic regression analysis to identify any possible independent predictive factors for in-hospital mortality or the need for bail-out IABP during the procedure. The finding that bail-out IABP-supported rotablation was associated with increased MACE and mortality rates was purely based on statistical results, but we believe that these findings reflect real-world practice as the patients were extremely old (78.5 ± 9.7 years), presented with ACS with shock in 58.4%, diabetes mellitus in 58.3% and the baseline LVEF was only 33.8%. Any procedure complications and hemodynamic compromise would result in catastrophic procedural results. Finally, this study only analyzed the patient characteristics and clinical outcomes in complex and very high-risk patients undergoing IABP-backed RA in contemporary practice. As other LV assistant devices other than ECMO are not available in our country, we do not know whether there are differences between IABP and other novel devices supporting rotablation in this particular group of patients. This remains to be studied.

CONCLUSIONS

In this study, RA under IABP assistance was carried out for very old patients with very high clinical risks, complex coronary anatomy and heavy calcification. A significant percentage of the patients needed RA to treat more than a single vessel and the treated length and stent length were long. Given the complexities of these lesions, the residual SYNTAX score remained high despite RA treatment. In spite of the clinical risks and lesion complexities, the in-procedure complications were quite acceptable. However, the in-hospital and short-term MACE rates remained high, but could be attributed to advanced patient age, multiple risk factors, comorbidities and severe LV dysfunction. We also found that bail-out IABP in these complex and high-risk patients was associated with significantly increased MACE and mortality rates, implying that the use of IABP should be implemented at the beginning of RA if a complex procedure is anticipated.

CONFLICT OF INTEREST

All authors declare no conflicts of interest.