Non-continuous mobile electrocardiogram monitoring for post-transcatheter aortic valve replacement delayed conduction disorders put to the test

Abstract

Aims

Permanent pacemaker implantation (PPM-I) remains nowadays the most important drawback of transcatheter aortic valve replacement (TAVR) procedure and the optimal strategy of delayed conduction disturbances (CDs) in these patients is unclear. The study aimed to validate an ambulatory electrocardiogram (ECG) monitoring through a 30 s spot ambulatory digital mobile ECG (AeECG), by using KardiaMobile-6L device in a 30-day period after TAVR procedure.

Methods and results

Between March 2021 and February 2022, we consecutively enrolled all patients undergoing TAVR procedure, except pacemaker (PM) carriers. At discharge, all patients were provided of a KardiaMobile-6L device and a spot digital ECG (eECG) recording 1 month schedule. Clinical and follow-up data were collected, and eECG schedule compliance and recording quality were explored. Among 151 patients without pre-existing PM, 23 were excluded for pre-discharge PPM-I, 18 failed the KardiaMobile-6L training phase, and 10 refused the device. Delayed CDs with a Class I/IIa indication for PPM-I occurred in eight patients (median 6 days). Delayed PPM-I vs. non-delayed PPM-I patients were more likely to have longer PR and QRS intervals at discharge. PR interval at discharge was the only independent predictor for delayed PPM-I at multivariate analysis. The overall eECG schedule compliance was 96.5%. None clinical adverse events CDs related were documented using this new AeECG monitoring modality.

Conclusion

A strategy of 30 s spot AeECG is safe and efficacious in delayed CDs monitoring after TAVR procedure with a very high eECG schedule level of compliance.

Graphical Abstract

Graphical Abstract.

(A) Flow chart programme for patient access to the device training phase and its rules. (B) eECG 1 month schedule. (C ) Histogram illustrating the number of cases and associated time to development of delayed CDs requiring PPM-I. CD, conduction disturbance; eECG, digital electrocardiogram; PPM-I, permanent pacemaker implantation.

What’s new?

• To our knowledge, we present the first single-centre study evaluating the incidence of post-transcatheter aortic valve replacement (TAVR) delayed conduction disturbances (CDs), using a non-continuous mobile electrocardiogram (ECG) monitoring with KardiaMobile 6L, in a 30-day interval after TAVR procedure.

• Delayed CDs with an indication for permanent pacemaker implantation occurred in 8% of patients, data in line with the most recent literature.

• Main findings of our 30 s spot ambulatory digital ECG monitoring are the safety, the patients empowering and compliance: nonclinical adverse events CDs related were recorded and the overall digital ECG schedule compliance level was very high.

• In this study we explored how to expand the use of this device beyond the common application of atrial fibrillation (AF) detection or QTc management providing a promising new way to promote remote post-TAVR outpatient management.

Introduction

Transcatheter aortic valve replacement (TAVR) use has increased significantly over the past 10 years.¹ Unlikely, the appearance of post-TAVR cardiac conduction disturbances (CDs) has not decreased over time, despite continuous improvements of transcatheter heart valve systems together with a really growing experience in this field.^2–4

These CDs are associated with increased morbidity and mortality for 1 year beyond the TAVR procedure, and the rate of permanent pacemaker (PM) implantation within the first 30 days remains a drawback of the procedure.^1,5–7

The coexistence of persistent post-TAVR delayed CDs problem, the recent and increasingly popular TAVR ‘minimalist’ approach, and the significantly rate of readmission for PPM-I have recently enhanced the post-procedural ambulatory electrocardiogram (AECG) monitoring use. Several studies have recently led to important insights regarding the occurrence and clinical impact of brady- and tachyarrhythmic events, using implantable cardiac monitor (ICM) or mobile cardiac telemetry (MCT) devices in a post-TAVR 7–30 days^8–11 or longer period.^12,13

Notwithstanding, the ICM or MCT modality, albeit offering continuous monitoring, has many disadvantages as frequent electrode changes and cost in the management of the devices and in the reporting.¹⁴

In this scenario, we aimed to evaluate the incidence of post-TAVR delayed CDs, by validating for the first time a 30 s spot digital electrocardiogram (eECG) remote monitoring, by using the new AliveCor® KardiaMobile 6L device in a 30-day period post-TAVR procedure.

Methods

Study population and recruitment

Between March 2021 and February 2022, we consecutively enrolled all patients scheduled for TAVR procedure at the University Hospital of Pisa, except those who were already a PM or implantable cardioverter-defibrillator carrier (Figure 1). Study protocol was submitted to the Ethics Committee of the University Hospital of Pisa for approval, data collection and analysis were approved by the institutional review board of our hospital, and a validation of the Privacy Impact Assessment was obtained. Written informed consents was obtained from all patients. Moreover, patients or their relatives had to demonstrate their ability to use a smartphone, sending and receiving text and email messages. Patients with a history of cognitive impairment and no caregivers and those unwilling to have their clinical data collected have been excluded from the study. For the recruitment, patients or their caregivers were required to have a smartphone compatible with the KardiaMobile 6L device. Particularly, before the enrolment, a mobile device training phase and acceptable response to the test were needed from both patients and relatives.

Figure 1.

Patient eligibility and enrolment.

Mobile device training phase

During the in-hospital stay, patients received the KardiaMobile 6L device, and a pseudo anonymized account registration was guided by the Authors, including the explanation to patients or their relatives about the device use, the dedicated application, how to record an eECG, and how to send the eECG to a dedicated study email. Patients/relatives who felt empowered and were able to independently record and send 3 consecutive good quality eECGs before the hospital discharge were automatically enrolled in the study and discharged with the device.

Study equipment

The handheld electrocardiogram device used in this study was the Food and Drug Administration cleared and Conformitè Europëenne marked AliveCor KardiaMobile 6L device.

This device is able to capture a medical-grade six-lead electrocardiogram (ECG) in 30 s; for more Tech Specs consult the web-page: https://store.alivecor.com/products/kardiamobile6l.

We decided to employ this device due to the availability of multiple peripheral ECG leads recording, pivotal for the diagnosis of conduction disorders like right or left bundle branch block (R/LBBB).

Clinical and procedural data

Standard 12-lead ECGs were collected at hospital admission and before discharge. Each 12-lead ECG was interpreted by a selected group of electrophysiologists working in our hospital. The predominant TAVR valve types implanted at our cardiac catheterization laboratory during the study period were from the Evolut series (Evolut-R, Evolut Pro and EvolutPro+, Medtronic, Dublin, Ireland) and Sapien 3 Ultra (Edwards Lifesciences, California). TAVR technique implantation, type, and valvular size, as vascular approach used, were done according to the last deployment techniques.

Post-procedural ambulatory digital electrocardiogram monitoring

Starting from the first day after hospital discharge, patients were asked to record and send a daily eECG for the first week and then once per week, up to the end of the 4-week follow-up (in total 10 eECG in the first month after TAVR procedure). Sent eECGs were analysed by dedicated cardiac electrophysiologist investigators. When the eECG was missing or considered of low quality an alert email was sent to the patient (i.e. reminding eECG’s scheduling and how to resolve artefacts occurrence). Phone call feedback was delivered exclusively in case of clinically relevant cardiac arrhythmia and/or conduction disorders detection. When needed, patients were admitted to our hospital electrophysiology unit and treated according to the clinical practice. At the end of the post-procedural ambulatory eECG monitoring period, patients were asked to express the level of satisfaction about the possibility of having a mobile ambulatory monitoring (‘on a scale of 1 to 5, how satisfied were you with this kind of ambulatory monitoring’?).

Digital electrocardiogram analysis

According to the latest Task Force on cardiac pacing and cardiac resynchronization therapy of the European Society of Cardiology developed in collaboration with the European Heart Rhythm Association,¹⁵ atrio-ventricular delayed CDs were defined as sinus rhythm with the presence of new onset or progression of a 1st degree atrioventricular block (AVB), new 2nd degree AVB type 1 and 2, 2:1, 3rd degree AVB, or alternating bundle branch block (BBB); intraventricular delayed CDs were defined as new right BBB (RBBB) or left BBB (LBBB). Median post TAVR in hospital stay was 2 days therefore CDs occurred later than 2 days after TAVR procedure were defined as delayed. Delta PR (ΔPR) and delta QRS (ΔQRS) interval were defined as the difference between the last PR and QRS length available 48 h after TAVR and the baseline PR and QRS length.

Statistical analysis

Categorical variables are shown as frequency and percentage. Continuous variables of normal distribution are shown as mean and standard deviation. Continuous variables of non-normal distribution are shown as median (25°–75° interquartile range).

All statistical analysis was performed with NCSS software, version 2021 (NCSS, LTD, Kaysville, UT, USA). Categorial variable were analysed using Pearson’s χ² test. The two-sample t-test and Mann–Whitney U test were used to analyse continuous variable respectively of normal and non-normal distribution. Receiver operating characteristic curves were used to determine best cutoffs for PR and QRS interval analysis. Multivariate analysis was performed using logistic regression adjusted for sex, age, and significant variables identified from univariate logistic regression. P values less than 0.05 were considered as significant.

Results

Clinical results

A total of 163 consecutive TAVR patients were evaluated; as shown in Figure 1, 12 patients were excluded due to pre-existing pacing device, 23 were excluded for pre-discharge PPM-I, 18 because failed the KardiaMobile-6L training phase, and 10 refused the device. Among the 23 patients excluded for pre-discharge PPM-I, the CD documented after TAVR and the relative Class of PM indication were represented as follows: 3° and advanced AVB (74%), new LBBB + bradycardia (17.4%), and other severe rhythm disturbances (8.6%) accounting for Class I and II indication for PPM-I of 74% and 26% respectively. In such cohort, the median total hospital stay was 6 days and median timing for PPM-I was 1 day (see Supplementary material online, Table S1).

Full clinical and demographic features, baseline medication and procedural data of the total of 100 enrolled patients are shown in Table 1. In the enrolled patients population, the overall mean age was 81.86 ± 6.28 years, and 39 (39%) patients were male; 90 (90%) patients were affected by arterial hypertension, 27 (27%) were diabetic, and 22 (22%) were affected by coronary artery disease. Mean left ventricle ejection fraction was 56.87 ± 9.19.

Table 1.

Baseline characteristics

	Overall	Delayed PM	No delayed PM	P
	(n = 100)	(n = 8)	(n = 92)
Clinical features
ȃAge, years	81.86 ± 6.28	81.07 ± 5.89	81.93 ± 6.34	0.70
ȃMale sex	39 (39%)	5 (62.5%)	34 (36.96%)	0.15
ȃBMI (kg/m2)	26.81 ± 4.36	25.91 ± 4.03	26.88 ± 4.40	0.38
ȃLogistic Euroscore, %	10.74 ± 9.82	8.17 ± 4.72	10.98 ± 1.14	0.69
ȃEuroSCORE II, %	3.91 ± 3.96	2.92 ± 1.23	4.00 ± 4.10	0.81
ȃSTS PROM score, %	3.76 ± 2.41	2.92 ± 1.16	3.85 ± 2.50	0.43
ȃArterial hypertension	90 (90%)	8 (100%)	82 (89.13%)	0.35
ȃDiabetes mellitus	27 (27%)	3 (37.5%)	24 (26.08%)	0.49
ȃCoronary artery disease	22 (22%)	3 (37.5%)	19 (20.65%)	0.24
ȃMitral regurgitation (moderate or severe)	15 (15%)	0 (0%)	15 (16.3%)	0.40
ȃLVEF, %	56.87 ± 9.19	58.13 ± 10.15	56.76 ± 9.16	0.55
ȃHistory of myocardial infarction	11 (11%)	0 (0%)	11 (11.96%)	0.30
ȃHistory of PCI	17 (17%)	2 (25%)	15 (16.30%)	0.36
ȃHistory of heart surgery	13 (13%)	1 (12.5%)	12 (13.04%)	0.96
ȃSerum creatinine, mg/dL	1.13 ± 0.46	1.34 ± 0.78	1.11 ± 0.42	0.58
ȃeGFR < 30 mL/min (Cockroft-Gault)	13 (13%)	2 (25%)	11 (11.96%)	0.30
ȃNYHA class ≥ 2	99 (99%)	8 (100%)	91 (98.91%)	0.94
Medications
ȃBeta-blocker	55 (55%)	5 (62.5%)	50 (54.35%)	0.66
ȃDHP CCB	20 (20%)	2 (25%)	18 (19.57%)	0.71
ȃASA	40 (40%)	3 (37.5%)	37 (40.22%)	0.88
ȃVKA	5 (5%)	0 (%)	5 (5.43%)	0.50
ȃDOAC	22 (22%)	4 (50%)	18 (19.57%)	0.05
Procedural data
ȃDeeper valve implantation	3 (3%)	0 (0%)	3 (3.26%)	0.61
ȃSelf-expandable valve	72 (72%)	3 (37.50%)	69 (75%)	0.02
ȃBalloon post-dilatation	30 (30%)	4 (50%)	26 (28.26%)	0.20

Data shown as % (n), as means ± (SD), and as median (Q1–Q3). Statistically significant variables were highlighted using bold and italic.

ASA, acetylsalicylic acid; BMI, body mass index; CCB, calcium channel blocker; DHP, dihydropyridine; DOAC, direct oral anticoagulant; eGFR, estimated glomerular filtration rate (Cockroft-Gault); LVEF, left ventricle ejection fraction; NYHA, New York Heart Association; PCI, percutaneous coronary intervention; PM, pacemaker; STS PROM, Society of Thoracic Surgeons Predicted Risk of Mortality; VKA, vitamin K antagonist.

At baseline ECG, five (5%) patients were in atrial fibrillation (AF), four (4%) patients showed 1st degree AVB, two (2%) right BBB, eight (8%) left anterior or left posterior fascicular block, and seven (7%) showed left BBB. Baseline mean PR interval was 168.94 ± 30.16 ms and the mean QRS duration was 93.98 ± 25.92 ms. Mean difference between baseline and discharge was 18.30 ± 47.80 ms for PR interval and 12.25 ± 26.25 ms for QRS interval. Respectively in 20% and 21% of patients, an increase of at least 20 ms for PR interval and 20 ms of QRS interval was observed. Full 12-lead ECG findings at baseline and discharge are listed in Table 2.

Table 2.

Twelve-lead electrocardiographic findings at baseline and discharge

	Overall	Delayed PM	No delayed PM	P
	(n = 100)	(n = 8)	(n = 92)
Baseline
ȃ1° AV delay	4 (4%)	1 (12.50%)	3 (3.26%)	0.20
ȃRBBB	2 (2%)	0 (0%)	2 (2.17%)	0.67
ȃLAFB or LPFB	8 (8%)	1 (12.50%)	7 (7.61%)	0.62
ȃLBBB	7 (7%)	0 (0%)	7 (7.69%)	0.42
ȃPR interval (ms)	168.94 ± 30.16	163.34 ± 36.70	169.42 ± 29.80	0.80
ȃQRS duration (ms)	93.98 ± 25.92	91.25 ± 16.42	94.23 ± 26.65	0.91
Discharge
ȃ1° AV delay	11 (11%)	2 (28.57%)	9 (9.79%)	0.13
ȃRBBB	4 (4%)	1 (12.50%)	3 (3.26%)	0.20
ȃLAFB or LPFB	11 (11%)	1 (12.50%)	10 (10.87%)	0.89
ȃLBBB	20 (20%)	2 (28.57%)	18 (19.78%)	0.58
ȃPR interval (ms)	184.62 ± 44.27	250.00 ± 53.29	179.17 ± 39.17	0.003
ȃQRS duration (ms)	104.35 ± 31.15	125 ± 33.38	102.55 ± 30.48	0.04
Δ PR (ms)a	18.30 ± 47.80	45 ± 84.01	15.81 ± 42.96	0.52
Δ PR ≥ 20 msa	19 (20.21%)	2 (25%)	17 (19.77%)	0.72
Δ QRS (ms)	12.25 ± 26.25	33.75 ± 40.34	10.38 ± 24.09	0.01
Δ QRS ≥ 20 ms	21 (21%)	4 (50%)	17 (18.48%)	0.04

Data shown as n (%). Statistically significant variables were highlighted using bold and italic.

AV, atrioventricular; LAFB, left anterior fascicular block; LBBB, left bundle branch block; LPFB, left posterior fascicular block; RBBB, right bundle branch block.

Patients in sinus rhythm only.

Delayed CDs with a Class I and Class IIa indication for PPM-I occurred in eight patients (8%) after a median of 6 days (range 4–8 days) post-TAVR (Table 3; Figure 2). In four of the eight patients who received a pacemaker implantation, hospital readmission happened before a clear Class for receiving PPM-I indication was met, due to the ongoing progression of CDs. In these four patients (#1, #5, #6, #7 as shown in Table 3), an in-hospital ECG Holter 24-h monitoring was applied promptly after hospital admission, and the Class of indication for PPM-I was met within 24 h.

Table 3.

Patients with delayed conduction disturbances post-TAVR, leading to PPM-I

Patient#	Age (years)	Sex	Valve type	Valve size (mm)	Baseline CDs	Discharge CDs	Delayed CDs leading to PPM-I	Days to event post-TAVR	PPM-I indication
1	78	F	Sapien 3	26	None	1st AVB + LBBB (PR 240 ms—QRS 180 ms)	2:1 AVB	8	Class I (C)
2	81	M	Sapien 2	29	LAFB	+ RBBB (ΔQRS +80 ms)	Alternating BBB	5	Class I (C)
3	82	F	Sapien Ultra	26	1st AVB	1st AVB (ΔPR +40 ms)	2nd AVB (M1) + dizziness	4	Class IIa (C)
4	69	F	Evolute PRO	29	None	LBBB (ΔQRS +60 ms)	+ HR RBBB Junctional rhythm	7	Class I (C)
5	86	M	Sapien 3	26	None	1st AVB (ΔPR +160 ms)	+ LBBB and 2:1 AVB	7	Class I (C)
6	80	M	Sapien 3	29	None	None	Pause (AF) > 4 s + dizziness	4	Class I (B)
7	89	M	Evolute PRO	29	None	None	Alternating BBB	4	Class I (C)
8	84	M	Evolute PRO	29	None	1st AVB (ΔPR +80 ms)	+ 2nd AVB (M1) + dizziness	7	Class IIa (C)

AF, atrial fibrillation; AV, atrioventricular; CDs, conduction disturbances; 1st/2nd AVB, first/second-degree atrioventricular block; HR, high rate; LAFB, left anterior hemiblock; L/RBBB, left/right bundle branch block; M1, Mobitz 1; PPM-I, permanent pacemaker implantation; TAVR, transcatheter aortic valve replacement.

Figure 2.

(A and B) eECG of patient# 2 showing AF with first RBBB and then alternating BBB; (C and D) eECG of patient# 3 (with dizziness) showing sinus rhythm with 1st AVB and then 2nd AVB type 1. AF, atrial fibrillation; AVB, atrioventricular block; BBB, bundle branch block; eECG, digital electrocardiogram; RBBB, right bundle branch block.

In comparison to patients who did not receive a PM implantation, those who underwent PPM-I were more likely to have a non-self-expandable valve (75% vs. 37.5%; P = 0.02) and to have a longer PR and QRS intervals at discharge (PR value: 250.00 ± 53.29 ms vs. 179.17 ± 39.17 ms; P = 0.003; QRS value: 125 ± 33.38 ms vs. 102.55 ± 30.48 ms; P = 0.04). At multivariate analysis, PR interval at discharge was demonstrated to be the only independent predictor for delayed PPM-I (multivariate OR 1.04; 95% C.I. 1.01–1.07; P = 0.04). Univariate and multivariate analysis results are shown in Table 4. Finally, no clinical adverse events CDs related (i.e. syncope) were recorded using this new mobile ambulatory mobile digital ECG (AeECG) monitoring modality, even if non continuous.

Table 4.

Univariate and multivariate analysis for delayed PM implant predictors

	Univariate			Multivariate
	Odds ratio	95% CI	P	Odds ratio	95% CI	P
Clinical features
ȃAge, years	0.98	0.88–1.09	0.72	0.95	0.81–1.10	0.45
ȃMale sex	2.84	0.63–12.65	0.16	3.04	0.23–40.41	0.40
ȃBMI (kg/m2)	0.94	0.79–1.13	0.53
ȃArterial hypertension	—		0.21
ȃDiabetes mellitus	1.70	0.38–7.66	0.50
ȃCoronary artery disease	2.53	0.52–12.29	0.26
ȃLVEF, %	1.02	0.93–1.11	0.68
ȃHistory of myocardial infarction	—		0.16
ȃHistory of PCI	2.27	0.37–13.54	0.39
ȃHistory of heart surgery	0.94	0.11–8.33	0.96
ȃSerum creatinine, mg/dL	2.37	0.64–8.72	0.22
ȃeGFR < 30 mL/min (Cockroft-Gault)	2.42	0.43–13.54	0.34
Medications
ȃBeta-blocker	0.71	0.16–3.17	0.65
ȃDHP CCB	1.37	0.26–7.36	0.72
Procedural data
ȃDeeper valve implantation	0		0.48
ȃSelf-expandable valve	0.2	0.04–0.9	0.03	0.27	0.03–2.77	0.27
ȃBalloon post-dilatation	2.35	0.55–10.10	0.26
12-lead ECG findings
ȃBaseline
ȃȃ1° AV delay	4.24	0.39–46.27	0.29
ȃȃRBBB	—		0.56
ȃȃLAFB or LPFB	1.73	0.19–16.17	0.64
ȃȃLBBB	0		0.27
ȃȃPR interval (ms)	0.99	0.97–1.02	0.63
ȃȃQRS duration (ms)	0.99	0.95–1.03	0.75
ȃDischarge
ȃȃ1° AV delay	3.69	0.62–21.84	0.18
ȃȃRBBB	4.24	0.39–46.27	0.29
ȃȃLAFB or LPFB	1.17	0.13–10.53	0.89
ȃȃLBBB	1.63	0.29–9.05	0.59
ȃȃPR interval (ms)	1 .04	1 .01–1.06	0 .0003	1 .04	1 .01–1.07	0 .04
ȃȃQRS duration (ms)	1.02	0.99–1.04	0.06	1.00	0.95–1.06	0.87
ȃȃΔ PR (ms)a	1.01	0.99–1.02	0.16
ȃȃΔ PR ≥ 20 msa	1.35	0.25–7.30	0.73
ȃȃΔ QRS (ms)	1 .02	1 .00–1.04	0 .04	1.00	0.95–1.06	0.95
ȃȃΔ QRS ≥ 20 ms	4.41	1.00–19.43	0.06	4.10	0.05–348.67	0.54

Statistically significant variables were highlighted using bold and italic.

AV, atrioventricular; BMI, body mass index; CI, confidence interval; DHP CCP, dihydropyridine calcium channel blocker; LAFB, left anterior fascicular block; LFPB, left posterior fascicular block; LVEF, left ventricle ejection fraction; PM, pacemaker; PCI, percutaneous coronary intervention; RBBB, right bundle branch block.

^aPatients in sinus rhythm only.

Digital results

Among the 163 consecutive TAVR patients, 18 (11.04%) were excluded because they failed the device training phase: non-compatible smartphone operating system or operating system version in 12 patients (7.3%), cognitive decline and lack of caregiver support in 3 patients (1.8%), and reduced mobility preventing correct device functioning in 3 patients (1.8%).

Excluding the smartphone app download phase, the in-hospital device training phase mean duration was 18 min (15–22 min).

The overall eECG schedule compliance level was 96.5%: a total of 965 eECG were sent, and 950 (98.4%) have been correctly recorded with an adequate quality for diagnosis and ECG interval measurements. Medium ranking score about patient satisfaction was 4.6.

Discussion

To our knowledge, we present the first single-centre study evaluating the incidence of post-TAVR delayed CDs, using a non-continuous mobile electrocardiogram monitoring in a 30-day interval after a TAVR procedure (Graphical Abstract).

The main findings of this study are as follows: (i) delayed CDs with a Class I/Class IIa indications for PPM-I occurred in a significant percentage of patients; (ii) delayed PPM-I patients were more likely to present longer PR and QRS interval at discharge, and the PR interval at discharge was the only independent predictor for delayed PPM-I; (iii) eECG schedule level compliance as eECG quality was extremely high; and (iv) albeit this ambulatory mobile electrocardiogram monitoring was not continuous, no clinical adverse events CDs related were recorded during the study.

Delayed conduction disturbances requiring a permanent pacemaker implantation after transcatheter aortic valve replacement

In our study, delayed CDs with a Class I/Class IIa indications for PPM-I occurred in 8% of patients with a median of 6 days (range 4–8 days) post-TAVR.

According to recent systematic reviews, the overall rate of PPM implantation after TAVR with new generation valves ranged between 2.3% and 36.1%,¹⁶ and it is lower when associated to balloon expandable valve compared to self-expandable valve.¹⁷

Part of this percentage is related to delayed PPM-I, and AECG using MCT at the time of hospital discharge after TAVR revealed high-degree atrioventricular (AV) or complete heart block warranting PPM-I in close to 10% of patients.¹⁴

More in detail, Toggweiler et al.¹⁸ evaluated the incidence of high grade AVB (H-AVB) after TAVR and defined as ‘delayed’ H-AVB (DH-AVB) occurring anytime between the immediate post-TAVR ECG and 30 days. Based on this definition, DH-AVB occurred in 6.7% of 1064 patients.¹⁸ Nevertheless, by using a different definition for delayed CDs, considering those events appearing ≥ 48 h post-TAVR, the percentage of patients developing DH-AVB dropped to 3.7%, with a median time of 3 days (range 2–8 days). On the other hand, the single-centre analysis by Mangieri et al. described that DH-AVB (still defined as occurring >2 days post-TAVR), was observed in 8.8% of 611 patients without pre-existing PPM.¹⁹

Likewise, Ream, among 150 consecutive TAVR patients without a prior pacing device and using the same definition of DH-AVB (as occurring > 2 days post-TAVR), reported an incidence of DH-AVB in 8% of total cohort with a median of 6 days (range 3 to 24 days) post-TAVR.⁷

As noted above, our result is in line with the most recent literature, despite difference in studies design. Indeed, we marked as ‘event’ the presence of delayed CDs (occurring >48 h post-TAVR) with a Class I and Class IIa indication for PPM-I, and we did not limit the definition to the onset of DH-AVB. This important methodology difference has been applied to guarantee a greater safety, considering the lack of a continuous AECG monitoring. The use of a spot 30 s ECG, however, did not impact our findings.

Interestingly, in our experience, PPM implantations occurred in the first week after TAVR as well as described by Toggweiler et al.¹⁸ and Ream et al.⁸

Electrocardiogram characteristics associated with the development of delayed cardiac disturbances

The most commonly reported indications of PPM implantation in the current TAVR practice are high-grade AVB, worsening or new onset LBBB, and progressive 1st degree AVB with LBBB.^20,21

More specifically, ECG predictors for delayed high-degree AVB have been documented as RBBB alone [odds ratio (OR): 20.46; 95% confidence interval (CI): 2.67–158.31; P = 0.004] and conduction disorders as LBBB or RBBB post-TAVR (OR: 10.8; 95%CI: 4.6–25.5; P < 0.01).^7,18

In the study of Ream et al., the event ‘DH-AVB’ was defined as the presence of any 2nd degree Mobitz II or 3rd degree AVB occurring within 2 days post-procedure and among 150 consecutive TAVR patients without a prior pacing device, DH-AVB vs. non-AVB patients were more likely to have RBBB.⁷

Besides, in the paper of Mangieri et al.,¹⁹ TAVR patients requiring late PPM-I for an ‘advanced CDs’ developed complete AV block, Mobitz type II block, pathological pauses, asystole, and symptomatic junctional rhythm. In this study, late PPM-I patients vs. non-PPM-I patients were more likely to have a significant widening of the PR and QRS intervals and at the multivariable analysis, ΔPR and baseline RBBB after TAVR were predictors of delayed advanced CD.

In our study, even if RBBB was observed in higher proportions among those who developed delayed indication for PPM, no significant statistical differences were found. However, according to previous studies, delayed PPM-I vs. non-delayed PPM-I patients were more likely to have a longer PR and QRS interval and this finding is in line with our study: at the multivariate analysis, PR interval at discharge was the only independent predictor for delayed pacing.

Probably, the differences in literature about delayed PPM-I ECG predictors after a TAVR procedure could be related to different definition of PPM-I event, as already described.

In our study, we defined event as the achievement of any kind of Class I or Class IIa indication for PPM-I. The rationale of this choice is that, unlike most of the studies previously published, we do not employ a 30-day continuous AECG monitoring but a 30 s spot mobile digital ECG with a precise schedule of recordings (a daily eECG during the first week and then once per week up to the end of the study’s follow-up). In this setting, we decided to intervene before the appearance of a high-grade AVB if the patient presented progressive CD and/or symptoms (i.e. 2nd AVB Mobitz 1 and dizziness).

Digital 30 s spot ambulatory mobile electrocardiogram monitoring modality performed by the AliveCor® KardiaMobile 6L device

Awareness of the risk for H-AVB after discharge is important to prompt development of risk stratification and monitoring protocols, and previous studies already published suggest that the use of real-time cardiac telemetric monitoring during the first 14 days after valve replacement could be useful for patients at risk for delayed high degree AVB.¹⁹

The breakthrough of our research is that we used for this purpose a completely different approach represented by an AeECG monitoring, mobile health guided and performed by a 30 s spot digital ECG.

In our study, we used the KardiaMobile 6L. This device has three electrodes that allow simultaneous recordings of all limbs leads by holding the device with both hands and applying the rear electrode against the left leg, and for this device, mean ECG interval duration measurements have been demonstrated to be comparable to supine standard 12-lead ECGs.²²

This peculiar feature was decisive for the purpose of this study: it allows the ECG detection of CDs previous mentioned. Furthermore, other advantages of KardiaMobile 6L are that it has a very good accuracy, with a sensitivity of 96.6% and a specificity of 94% for AF detection, and, if compared with other MCT devices, it has a lower cost, could be easily reused, has a good battery autonomy, and is not burdened with the durability of the adhesives or the need of frequent electrode changes.²³

Finally, peculiar ‘digital’ findings of our novel AeECG approach are the safety, the patients empowering and compliance. Even if the devices do not continuously record the heart rhythm, no clinical adverse events due to CDs were found using this new AeECG monitoring modality. Variables such as age, educational background, and socioeconomic status did not impact the ability to develop a digital health literacy needed for the enrolment (only 11.04% of patients were excluded because they failed the device training phase). The overall eECG schedule level compliance was indeed 96.5%, with a very high percentage of good quality traces (950/965 sent eECG, 98.4) due to the increasingly widespread familiarity of the population with technology. Finally, in this study, we tried to expand the use of this device beyond the common application of AF detection or QTc management providing a promising new way to promote remote post-TAVR outpatient management.

Limitations

The present study holds several limitations. First, this is a single-centre, prospective, and non-controlled study; the trial was not designed in order to highlight clinical differences between home ECG monitoring and a usual care strategy. The study, even though a significant proportion of subjects underwent PPM-I due to rhythm disturbances, was not explicitly designed nor powered to assess the rate of such events in the post-procedural period and, notably, was not specifically powered for PPM-I predictors assessment. The correlation, for example, between delayed PPM-I and having a non-self-expandable valve found at the univariate analysis was lost at the multivariate one. In fact, in our study the group of patients receiving balloon-expandable valves was small, with only four incidences of CD, which might represent a study limitation. Moreover a 6-lead ECG, while representing a huge step forward from single lead tracings, still lacks the complete picture that only a standard 12-lead recording is able to deliver, with potential underdiagnosis.

Conclusion

The occurrence of delayed CDs with an indication for PPM-I remains nowadays the most important drawback of the TAVR procedure. In our study, this novel ambulatory mobile electrocardiogram monitoring modality based on a 30 s spot AeECG was seen to be safe and helpful in a prompt identification and early treatment of post-TAVR outpatients with a very high eECG schedule level of compliance. Further prospective studies are needed for a better patient selection and outpatient monitoring, making the early post-TAVR discharge approach even safer and mobile health guided.

Supplementary material

Supplementary material is available at Europace online.

Funding

None declared.

Data availability

Data cannot be shared for ethical/privacy reasons. The data underlying this article cannot be shared publicly for the privacy of individuals that participated in the study. The data will be shared on reasonable request to the corresponding author.