Abstract
Electrical cardioversion (ECV) is recommended for rhythm control in atrial arrhythmia patients, yet ECV use and outcomes in contemporary practice are unknown. We reviewed all non-emergent ECVs for atrial arrhythmias at a tertiary care center (2010–2013), stratifying patients by transesophageal echocardiography (TEE) use pre-ECV and comparing demographics, history, vitals, and laboratory studies. Outcomes included post-procedure success and complications, and repeat cardioversion, rehospitalization, and death within 30 days. Overall, 1017 patients underwent ECV; 760 (75%) for atrial fibrillation and 240 (24%) for atrial flutter; 633 underwent TEE pre-ECV and 384 did not. TEE recipients were more likely to be inpatients (74% vs. 44%, p<0.001), have higher mean CHADS2 scores (2.6 vs. 2.4, p=0.03), and lower mean international normalized ratios (1.2 vs. 2.1, p<0.001). Overall, 89 (8.8%) did not achieve sinus rhythm and 14 experienced procedural complications (1.4%). Within 30 days, 80 (7.9%) underwent repeat ECV, 113 (11%) were rehospitalized, and 14 (1.4%) died. Although ECV success was more common in patients who underwent TEE pre-ECV (77% vs. 68%, p=0.01), there were no differences in 30-day death or rehospitalization rates (11.1% vs. 13.0%, p=0.37). In multivariable analyses, higher pre-ECV heart rate was associated with increased rehospitalization or death (adjusted HR 1.15/10 bpm, 95% CI 1.07–1.24, p<0.001), while TEE use was associated with lower rates (adjusted HR 0.58, 95% CI 0.39–0.86, p=0.007). In conclusion, failures, complications, and rehospitalization following non-emergent ECV are common, and associated more with patient condition than procedural characteristics. TEE use was associated with better clinical outcomes.
Keywords: Atrial fibrillation, Cardioversion, Transesophageal echocardiography, Outcomes
In hopes of better understanding ECV use and outcomes, we sought to: 1) describe a contemporary cohort of patients undergoing non-emergent cardioversion at a major tertiary care hospital, with or without pre-procedure transesophageal echocardiography (TEE); 2) explore the outcomes in patients undergoing cardioversion; and 3) identify factors associated with adverse outcomes following cardioversion.
Methods
We included consecutive patients who underwent non-emergent ECV at Duke University Medical Center from January 2010 to March 2013. Both inpatient and outpatient procedures were included, as long as they occurred in the cardioversion “suite,” which is a unified location for all non-emergent ECVs at our institution (pharmacologic cardioversions are not performed in this setting). For patients with multiple cardioversions during the study period, the first procedure was included in the analysis as the index event. In order to identify non-emergent cardioversions unrelated to invasive cardiac procedures or catastrophic protracted hospitalizations, several exclusion criteria were used. Cardioversions performed in the electrophysiology laboratories and those for ventricular arrhythmias were not included. Additionally, to provide more clinically-relevant insights, we excluded patients with cardiac surgery or catheter ablation for AF within 90 days prior to cardioversion, those with metastatic cancer, and inpatients with hospitalizations for >14 days prior to cardioversion.
Baseline demographics, medical history, laboratory results, administrative data, and clinical outcomes were derived from the electronic health record and based on clinical diagnosis, including both laboratory and billing systems, via the Decision Support Repository at Duke University. Risk scores for stroke in patients with AF (Congestive heart failure, Hypertension, Age ≥75 years, Diabetes mellitus, Stroke or TIA or thromboembolism [CHADS2] and Congestive heart failure, Hypertension, Age ≥75 years, Diabetes mellitus, Stroke or TIA or thromboembolism, Vascular disease, Age 65–74 years, Sex category [CHA2DS2-VASc]) were calculated using previously-described methods.1,2 Periprocedural data on the cardioversion procedure and immediate outcomes were analyzed from the clinical cardioversion procedure log, which is a database that includes pre-procedure vital signs and rhythm, inpatient status, anesthesia details, cardioversion approach, post-cardioversion vital signs and rhythm, and immediate complications. The procedure log is part of the medical documentation and record for each patient undergoing ECV at Duke University. Detailed ambulatory and inpatient medication use were not available.
Patient outcomes included immediate periprocedural complications, failed cardioversion, repeat cardioversion, thromboembolic events, rehospitalization (with cause), or death within 30 days. Periprocedural complications were derived from the procedure log and defined as bradycardia requiring treatment (medical or electrical), cardiac arrest, hypotension requiring treatment, significant hypoxia, or additional arrhythmia requiring treatment (e.g., ventricular tachycardia, ventricular fibrillation). Failed cardioversion was defined as any periprocedural complication (as above), or a post-cardioversion rhythm of AF, atrial flutter, atrial tachycardia, or low atrial rhythm. All repeat hospitalizations and death within the Duke University Health System were captured through the Decision Support Repository, which is an electronic clearinghouse for clinical data within the health system. Cause of hospitalizations and deaths were identified through primary review of the medical record with categorization of events using the primary clinical diagnosis for the hospitalization and cause of death in the death summaries. To identify factors associated with adverse clinical outcomes, we used the composite endpoint of rehospitalization or death within 30 days of the procedure.
In order to capture TEEs most likely to be performed in anticipation of cardioversion, we stratified baseline and procedural characteristics by the use of TEE within 7 days prior to cardioversion. Distribution of TEE timing was assessed to confirm the validity of this approach. Categorical variables are described as number and percentage and compared using Pearson Chi-square tests; continuous variables are described as median and 25th–75th percentiles and compared using Wilcoxon rank-sum tests.
Immediate post-cardioversion characteristics and cardioversion success is described and compared by TEE use, CHADS2 scores, and CHA2DS2-VASc scores using similar chi-square tests. Thirty-day rehospitalization or death was evaluated with Kaplan-Meier curves and log-rank tests by these same key variables.
Multivariate Cox proportional hazards regression was used to identify and describe factors associated with death or rehospitalization within 30 days in this patient cohort. Models were derived using backward selection, with a stay criterion of p<0.10. Candidate variables for selection included baseline patient characteristics, medical history, pre-procedure vital signs, pre-procedure rhythm, use of pre-procedure TEE, inpatient status, and cardioversion shock mechanism. All candidate variables were assessed for linearity and proportional hazards assumptions. There were no relevant proportional hazards violations; linearity was addressed using linear splines when needed. Subsequently, we added pre-procedural laboratory data as candidate covariates using the same modeling approach; however, this was limited to the subset of 896 patients (88%) with laboratories available within 30 days prior to the procedure. We further assessed the impact of including immediate post-cardioversion results in the model of 30-day outcomes, using the same backward-selection procedure with the added consideration of post-cardioversion vitals, post-cardioversion rhythm, or immediate post-cardioversion complication, as candidate covariates.
This analysis was approved by the Institutional Review Board of Duke University, which granted a waiver of informed consent. All statistical analyses of aggregate, de-identified data were performed at the Duke Clinical Research Institute using SAS software (version 9.2 or higher, SAS Institute, Cary, NC). No extramural funding support was used.
Results
A total of 1229 patients undergoing non-emergent cardioversion were identified, with a total of 1663 cardioversion procedures recorded. After applying exclusion criteria, this yielded a final study cohort of 1017 patients undergoing their first cardioversion during the study period (Figure 1). Overall, 60% (n=608) of patients were hospitalized as inpatients at the time of their index procedure; the mean time from cardioversion to discharge was 3.5 days.
Figure 1. Study cohort.
This figure displays the derivation of the study cohort.
TEE = transesophageal echocardiogram
Baseline characteristics and procedural details, stratified by TEE use, are shown in Table 1. Imaging findings within the cohort are shown in Table 2, with unadjusted, immediate post-cardioversion outcomes in Table 3. Overall, 8.8% of patients (n=89) failed to achieve sinus rhythm following cardioversion and there were 14 immediate complications (1.4%) in 13 patients (1.3%). Rates of ECV failure or complication were not significantly different between patients with versus without TEE (9.5% vs. 9.6%, p=0.93), or by CHADS2 (9.8% for ≥2 vs. 8.7% for 0–1, p=0.59) or CHA2DS2-VASc scores (9.7% for ≥2 vs. 8.2% for 0–1, p=0.61).
Table 1.
Baseline Characteristics, Stratified by Use of TEE Within 7 Days Prior to Cardioversion
| Overall (n=1017) | TEE Prior to Cardioversion (n=633) | Cardioversion without TEE (n=384) | p-value | |
|---|---|---|---|---|
| Age, median (IQR) | 68 (59–76) | 68 (60–76) | 69 (59–76) | 0.7 |
| Female | 351/1016 (35%) | 232/632 (37%) | 119/384 (31%) | 0.06 |
| Inpatient | 632/1017 (62%) | 465/633 (74%) | 167/384 (44%) | <0.001 |
| Hypertension | 858/1017 (84%) | 531/633 (84%) | 327/384 (85%) | 0.6 |
| Diabetes | 342/1017 (34%) | 232/633 (37%) | 110/384 (29%) | 0.009 |
| Renal failure | 265/1017 (26%) | 187/633 (30%) | 78/384 (20%) | 0.001 |
| Smoker | 315/1017 (31%) | 199/633 (31%) | 116/384 (30%) | 0.7 |
| Hyperlipidemia | 659/1017 (65%) | 417/633 (66%) | 242/384 (63%) | 0.4 |
| Heart failure* | 578/1017 (57%) | 381/633 (60%) | 197/384 (51%) | 0.006 |
| Coronary heart disease* | 510/1017 (50%) | 319/633 (50%) | 191/384 (50%) | 0.8 |
| Prior myocardial infarction | 229/1017 (23%) | 145/633 (23%) | 84/384 (22%) | 0.7 |
| Prior cerebrovascular disease | 244/1017 (24%) | 160/633 (25%) | 84/384 (22%) | 0.2 |
| Peripheral vascular disease | 128/1017 (13%) | 86/633 (14%) | 42/384 (11%) | 0.2 |
| Chronic obstructive pulmonary disease | 79/1017 (7.8%) | 57/633 (9.0%) | 22/384 (5.7%) | 0.06 |
| Prior liver disease | 37/1017 (3.6%) | 23/633 (3.6%) | 14/384 (3.6%) | 1.0 |
| CHADS2 score, mean (SD) | 2.5 (1.5) | 2.6 (1.5) | 2.4 (1.5) | 0.03 |
| CHADS2 score ≥2 | 742/1017 (73%) | 472/633 (75%) | 270/384 (70%) | 0.1 |
| CHA2DS2-VASc score, mean (SD) | 4.0 (2.1) | 4.1 (2.1) | 3.9 (2.1) | 0.07 |
| CHA2DS2-VASc score ≥2 | 906/1016 (89%) | 574/632 (91%) | 332/384 (87%) | 0.03 |
| TEE same day as cardioversion | 575/1017 (57%) | 575/633 (91%) | - | - |
| Pre-cardioversion vital signs | ||||
| Diastolic blood pressure (mm Hg), median (IQR) | 76 (66–86) | 75 (66–86) | 76 (67–86) | 0.6 |
| Systolic blood pressure (mm Hg), median (IQR) | 128 (114–144) | 128 (114–143) | 129 (114–145) | 0.7 |
| Heart rate, median (IQR) | 89 (74–110) | 91 (77–113) | 83 (71–102) | <0.001 |
| Labs prior to cardioversion | ||||
| Hemoglobin (g/dL), median (IQR) | 14 (12–15) | 13 (12–15) | 14 (12–15) | 0.06 |
| Platelets (x103), median (IQR) | 210 (172–253) | 213 (173–260) | 205 (170–238) | 0.01 |
| International normalized ratio, median (IQR) | 1.4 (1.1–2.3) | 1.2 (1.0–1.9) | 2.1 (1.2–2.7) | <0.001 |
| aPTT (seconds), median (IQR) | 35 (29–42) | 32 (29–39) | 39 (35–44) | <0.001 |
| Creatinine (mg/dL), median (IQR) | 1.1 (0.9–1.4) | 1.1 (0.9–1.4) | 1.1 (0.9–1.4) | 0.04 |
| Potassium (mmol/L), median (IQR) | 4.2 (3.9–4.5) | 4.2 (3.8–4.5) | 4.3 (4.0–4.5) | 0.03 |
| Magnesium (mg/dL), median (IQR) | 2.1 (1.9–2.2) | 2.1 (1.9–2.2) | 2.1 (1.9–2.2) | 0.4 |
| Pre-cardioversion rhythm | 0.007 | |||
| Atrial fibrillation | 760/1017 (75%) | 452/633 (71%) | 308/384 (80%) | |
| Atrial flutter | 240/1017 (24%) | 170/633 (27%) | 70/384 (18%) | |
| Atrial tachycardia | 17/1017 (1.7%) | 11/633 (1.7%) | 6/384 (1.6%) | |
| Cardioversion via implanted device | 12/949 (1.3%) | 6/593 (1.0%) | 6/356 (1.7%) | 0.4 |
| Cardioversion sedation | ||||
| Propofol | 973/1017 (96%) | 608/633 (96%) | 365/384 (95%) | 0.4 |
| Propofol dose (mg), median (IQR) | 110 (80–160) | 140 (100–200) | 80 (60–100) | <0.001 |
| Midazolam | 7/1017 (0.7%) | 4/633 (0.6%) | 3/384 (0.8%) | 1.000 |
| Fentanyl | 11/1017 (1.1%) | 6/633 (0.9%) | 5/384 (1.3%) | 0.8 |
aPTT = activated partial thromboplastin time; CHADS2 = ; CHA2D2-VASc = ; IQR = interquartile range; mg, milligram; SD = standard deviation; TEE = transesophageal echocardiogram
Based on clinical diagnosis codes in the electronic health record, as documented by the treating physician.
Table 2.
Imaging findings among patients undergoing cardioversion.*
| Overall (n=1017) | TEE Prior to Cardioversion (n=633) | Cardioversion without TEE (n=384) | p-value | |
|---|---|---|---|---|
| LA Size | 0.691 | |||
| Normal | 142/691 (20.5%) | 94/448 (21.0%) | 48/243 (19.8%) | |
| Small | 1/691 (0.1%) | 1/448 (0.2%) | 0/243 (0.0%) | |
| Mildly enlarged | 331/691 (47.9%) | 220/448 (49.1%) | 111/243 (45.7%) | |
| Moderately enlarged | 196/691 (28.4%) | 120/448 (26.8%) | 76/243 (31.3%) | |
| Severely enlarged | 21/691 (3.0%) | 13/448 (2.9%) | 8/243 (3.3%) | |
| MV Leaflets | <.001 | |||
| Normal | 784/879 (89.2%) | 563/613 (91.8%) | 221/266 (83.1%) | |
| Abnormal | 95/879 (10.8%) | 50/613 (8.2%) | 45/266 (16.9%) | |
| MV Mobility | 0.525 | |||
| Fully mobile | 846/877 (96.5%) | 591/611 (96.7%) | 255/266 (95.9%) | |
| Partially mobile | 31/877 (3.5%) | 20/611 (3.3%) | 11/266 (4.1%) | |
| Completely immobile | 0/877 (0.0%) | 0/611 (0.0%) | 0/266 (0.0%) | |
| LVEF | 0.750 | |||
| <15% | 33/826 (4.0%) | 23/568 (4.0%) | 10/258 (3.9%) | |
| 20% | 30/826 (3.6%) | 18/568 (3.2%) | 12/258 (4.7%) | |
| 25% | 35/826 (4.2%) | 25/568 (4.4%) | 10/258 (3.9%) | |
| 30% | 25/826 (3.0%) | 18/568 (3.2%) | 7/258 (2.7%) | |
| 35% | 29/826 (3.5%) | 16/568 (2.8%) | 13/258 (5.0%) | |
| 40% | 49/826 (5.9%) | 35/568 (6.2%) | 14/258 (5.4%) | |
| 45% | 53/826 (6.4%) | 36/568 (6.3%) | 17/258 (6.6%) | |
| 50% | 88/826 (10.7%) | 65/568 (11.4%) | 23/258 (8.9%) | |
| >55% | 484/826 (58.6%) | 332/568 (58.5%) | 152/258 (58.9%) | |
| Preserved LVEF (≥50) | 572/826 (69.2%) | 397/568 (69.9%) | 175/258 (67.8%) | 0.551 |
LA: left atrium; MV: mitral valve; LVEF: left ventricular ejection fraction
Based on most recent transthoracic or transesophageal echocardiogram within the prior year.
Table 3.
Unadjusted Immediate Post-cardioversion Outcomes
| Variable | Overall (n=1017) | TEE Prior to Cardioversion (n=633) | Cardioversion without TEE (n=384) | p-value |
|---|---|---|---|---|
| Post-cardioversion vital signs | ||||
| Diastolic blood pressure (mm Hg), median (IQR) | 63 (56–72) | 62 (55–70) | 65 (58–74) | <0.001 |
| Systolic blood pressure (mm Hg), median (IQR) | 111 (98–127) | 109 (96–124) | 117 (103–130) | <0.001 |
| Heart rate, median (IQR) | 67 (59–76) | 69 (60–78) | 65 (55–74) | <0.001 |
| Post-cardioversion rhythm | 0.01 | |||
| Atrial fibrillation | 65/1017 (6.4%) | 39 (6.2%) | 26 (6.8%) | |
| Atrial flutter | 11/1017 (1.1%) | 6 (0.9%) | 5 (1.3%) | |
| Atrial tachycardia | 1/1017 (0.1%) | 1 (0.2%) | 0 (0.0%) | |
| Low atrial rhythm | 12/1017 (1.2%) | 7 (1.1%) | 5 (1.3%) | |
| Normal sinus rhythm | 748/1017 (74%) | 488 (77%) | 260 (68%) | |
| Sinus bradycardia | 180/1017 (18%) | 92 (15%) | 88 (23%) | |
| Any complication* | 13/1017 (1.3%) | 11/633 (1.7%) | 2/384 (0.5%) | 0.1 |
| Bradycardia requiring treatment | 4 (0.4%) | 4 (0.6%) | 0 | |
| Cardiac arrest | 1 (0.1%) | 1 (0.2%) | 0 | |
| Hypotension requiring treatment | 4 (0.4%) | 3 (0.5%) | 1 (0.3%) | |
| Hypoxia | 2 (0.2%) | 2 (0.3%) | 0 | |
| VT/VF requiring treatment | 1 (0.1%) | 0 | 1 (0.3%) | |
| Other arrhythmia | 2 (0.2%) | 2 (0.3%) | 0 | |
In total, 80 patients (7.9%) underwent repeat cardioversion within 30 days; these included 23 patients (24%) with a cardioversion failure or immediate complication during the index procedure. The incidence of repeat cardioversion tended to be higher in patients with prior TEE versus those without (8.5% vs. 6.8%, p=0.31), and in those with higher CHADS2 (8.4% for ≥2 vs. 6.6% for 0–1, p=0.34) and CHA2DS2-VASc scores (8.3% for ≥2 vs. 4.6% for 0–1; p=0.17).
Among 113 rehospitalization events within 30 days, there was 1 stroke (0.1% overall), 2 transient ischemic attacks (TIAs; 0.2% overall), and 2 admissions for bleeding (0.2% overall). The remaining 65 hospitalizations were for atrial arrhythmias (64 for AF), 1 for ventricular tachycardia, 10 for heart failure, 8 for other cardiovascular causes, and 24 for non-cardiovascular and non-bleeding reasons. Fourteen patients (1.4%) died within 30 days of cardioversion: 5 due to heart failure, 2 due to respiratory failure, 2 from septic shock, and for 5 patients, a cause was not available.
Kaplan-Meier event curves for the first occurrence of death or rehospitalization, stratified by use or non-use of TEE were not significantly different and are shown in Figure 2A (11.1%, 95% confidence interval [CI] 8.9%–13.9% with TEE vs. 13.0%, 95% CI 10.0%–16.9% without TEE; plog-rank=0.4 comparison between TEE vs. no TEE). Kaplan-Meier rates of death or hospitalization were significantly higher in patients with CHADS2 scores ≥2 (event rate 13.4%, 95% CI 11.1%–16.0% vs. 7.6%, 95% CI 5.0%–11.6% for scores 0–1; plog-rank=0.02, Figure 2B), and in patients with CHA2DS2-VASc scores ≥2 (event rate 12.8%, 95% CI 10.8%–15.2% vs. 3.8%, 95% CI 1.4%–9.8% for scores 0–1; plog-rank=0.009, Figure 2C). Additional, subgroup analyses demonstrated worse outcomes in those with prior heart failure, compared to no prior heart failure (Supplemental Data).
Figure 2. Death or hospitalization.
Kaplan-Meier events curves for death or hospitalization, stratified by use of TEE within 7 days prior to cardioversion (Panel A), by CHADS2 scores (Panel B), and by CHA2DS2-VASc scores (Panel C).
TEE = transesophageal echocardiogram
Results of multivariable, Cox proportional hazards regression models are shown in Table 4. Clinical factors associated with 30-day outcomes were similar in models that did or did not include pre-procedural laboratory data. The use of pre-procedure TEE was associated with lower 30-day rehospitalization or death in models excluding (adjusted HR 0.67, 95% CI 0.46–0.97, p=0.04) and including (adjusted HR 0.58, 95% CI 0.39–0.86, p=0.007) laboratory data. However, neither immediate post-cardioversion outcomes (vital signs, rhythm, or complications) nor inpatient status was associated with 30-day rehospitalization or death.
Table 4.
Factors Associated with Rehospitalization or Death Following Cardioversion*
| Model Using Only Clinical Characteristics (n=1017) | Model Including Laboratory Data (n=896) | ||||
|---|---|---|---|---|---|
| HR (95% CI) | p-value | HR (95% CI) | p-value | ||
| Ischemic heart disease | 0.61 (0.38 – 0.97) | 0.04 | Simultaneous TEE | 0.58 (0.39 – 0.86) | 0.007 |
| Simultaneous TEE | 0.67 (0.46 – 0.97) | 0.04 | Ischemic heart disease | 0.65 (0.40 – 1.07) | 0.09 |
| SBP per 10mmHg >120mmHg | 0.86 (0.76 – 0.99) | 0.03 | SBP per 10mmHg >120mmHg | 0.82 (0.71 – 0.96) | 0.01 |
| Age per 10 years | 1.14 (0.98 – 1.34) | 0.1 | Platelets per 10k (up to 150) | 0.85 (0.77 – 0.94) | 0.001 |
| Heart rate per 10 bpm | 1.17 (1.09 – 1.25) | <0.001 | Platelets per 10k (above 150) | 1.03 (1.00 – 1.05) | 0.06 |
| Chronic kidney disease | 1.44 (0.96 – 2.16) | 0.08 | Heart rate per 10 bpm | 1.15 (1.07 – 1.24) | <0.001 |
| Hyperlipidemia | 1.60 (1.00 – 2.54) | 0.049 | Age per 10 years | 1.21 (1.02 – 1.43) | 0.03 |
| COPD | 1.68 (0.98 – 2.89) | 0.06 | Hyperlipidemia | 1.48 (0.90 – 2.41) | 0.1 |
| Prior MI | 1.68 (1.06 – 2.69) | 0.03 | Prior MI | 1.53 (0.94 – 2.49) | 0.09 |
| CHF | 1.74 (1.11 – 2.74) | 0.02 | COPD | 1.61 (0.90 – 2.86) | 0.1 |
| CHF | 1.63 (1.00 – 2.65) | 0.048 | |||
| Chronic kidney disease | 1.67 (1.10 – 2.55) | 0.02 | |||
Vital signs and lab values are all prior to cardioversion.
bpm = beats per minute; CHF = congestive heart failure; CI = confidence interval; HR = hazard ratio; All other abbreviations can be found in Table 1.
Discussion
We believe our analysis of more than 1,000 cardioversions is the largest cohort describing clinical outcomes of ECV in the United States. We found that TEE was used in the majority (62%) of these procedures. Approximately 1 in 10 patients experienced an immediate adverse outcome or a failed cardioversion, and more than 1 in 10 patients were either rehospitalized or died within 30 days of the procedure. In multivariable analysis, several factors were associated with increased 30-day death or rehospitalization, and may provide opportunities for interventions to reduce such events following ECV.
To date, contemporary data on the use and outcomes of ECV have been limited to international cohorts, or subgroups of clinical trials. The International Registry on Cardioversion of Atrial Fibrillation (RHYTHM-AF) enrolled 3,940 patients with recent AF who were referred for cardioversion in Australia, Brazil, and Europe.3 The clinical outcomes of this study have recently been published.4 Among the 75% of patients who ultimately underwent cardioversion in RHYTHM-AF, conversion to normal sinus rhythm was successful in 90%, with very low rates of adverse clinical events. Our analysis was performed using data from a single high volume center in the United States, and included patients undergoing ECV with new recent AF (as in RHYTHM-AF), as well as those patients with chronic arrhythmia and other comorbidities. Our study confirms the high rate of immediate cardioversion success that was observed in RHYTHM-AF, yet our data also demonstrate a high burden of healthcare utilization following cardioversion.
Other studies of clinical outcomes following cardioversion have predominantly focused on thromboembolic events. The Finnish CardioVersion (FinCV) study, which was the largest study of post-cardioversion outcomes, identified a significant risk of thromboembolism, particularly in patients undergoing cardioversion without post-procedure anticoagulation.5 In contrast, several subgroup analyses of cardioversion in clinical trials of non-vitamin K oral anticoagulants yielded low rates of adverse events,6–8 as anticoagulation in these patients was carefully managed; nonetheless, only 1 of these analyses included rates of post-cardioversion hospitalization.8 Data from the Rivaroxaban Once Daily Oral Direct Factor Xa Inhibition Compared with Vitamin K Antagonism for Prevention of Stroke and Embolism (ROCKET-AF) trial demonstrated an approximate 6.8% hospitalization rate within 30 days following cardioversion.
Our cohort demonstrates that hospitalization within 30 days post-cardioversion is not specific to a clinical trial population; rather, hospitalization following cardioversion is likely to be even higher in clinical practice. Hospitalization after cardioversion appears to be driven by specific patient characteristics; in addition to medical comorbidities (e.g., ischemic heart disease, hyperlipidemia, kidney disease, etc.), pre-cardioversion heart rate and blood pressure were independently and significantly associated with events at 30 days. While vital signs may reflect generally poor stability prior to cardioversion, they also likely represent a high hemodynamic burden of arrhythmia. There is some debate regarding the intensity of chronic heart rate control in patients with AF,9–11 yet our data suggest that patients with better-controlled heart rates prior to cardioversion are less likely to be readmitted following the procedure.
Importantly, patients undergoing TEE prior to cardioversion had a small numerical increase in the number of periprocedural complications (likely related to increased anesthesia and esophageal intubation), but the use of TEE was associated with a lower risk of death or rehospitalization at 30 days. This finding likely reflects selection biases and/or residual confounding in the use of TEE: patients have more recent-onset arrhythmia, they may be a more carefully-treated population, and their subsequent referral for ECV likely indicates benign TEE findings. While a diagnostic test like TEE is rarely causally linked to improved outcomes, it does appear to be a valid marker. Similarly, stratification by stroke risk score yielded differences in outcomes, as patients with higher CHADS2 and CHA2DS2-VASc scores had significantly higher event rates; this finding is consistent with prior data demonstrating the applicability of these scores to predict a broad range of clinical outcomes.12–15
Our study had several limitations. First, our data are based on a retrospective, observational analysis that took place during a specific period of time at a single tertiary referral institution, and used electronic health record and administrative data. As a result, there may be selection and follow-up biases, as well as residual and/or unmeasured confounding.16 Second, details of medical therapy at the time of cardioversion—specifically anticoagulation and antiarrhythmics—are not available. Third, rehospitalization events are limited to a single health system, which likely means that these data underestimate true rehospitalization rates. Fourth, specific events, such as thromboembolism and death, are relatively rare, consequently limiting our ability to draw inferences about predictive factors. Finally, findings from TEEs are not provided, since this was not the primary focus of our analysis. Furthermore, TEEs and other tests performed prior to ECV are principally used to assess the presence of left atrial or left atrial appendage thrombus; as a result, there were unlikely to be thrombogenic findings precluding the procedure since all patients underwent a cardioversion.
Supplementary Material
Table S1. Unadjusted Post-cardioversion Outcomes by Heart Failure Status
Acknowledgments
The authors would like to acknowledge Erin Hanley, MS, for her editorial contributions to this manuscript. Ms. Hanley did not receive compensation for her contributions, apart from her employment at the institution where this study was conducted.
Funding sources: This work was supported internally by the Duke Clinical Research Institute.
Footnotes
Conflict of Interest Disclosures
BA Steinberg: Dr. Steinberg reports funding from NIH T-32 training grant #5 T32 HL 7101-38.
P Schulte: Dr. Schulte has no relevant disclosures to report.
P Hofman: Dr. Hofman has no relevant disclosures to report.
M Ersbøll: Dr. Ersbøll has no relevant disclosures to report.
JH Alexander: Dr. Alexander reports research funding from Bristol Myers Squibb, Boehringer Ingelheim, CLS Behring, Duke Health System, National Institutes of Health, Oxygen Biotherapeutics, Perosphere, REgado Biosciences, and Vivus Pharmaceuticals (all significant); consulting, honoraria, or other services (including CME) from Portola and Regado Biosciences (modest), Duke Private Diagnostic Clinic (significant); and reimbursement for personal expenses from Bristol Myers Squibb ($5–25K).
L Broderick-Forsgren: Dr. Broderick-Forsgren has no relevant disclosures to report.
KJ Anstrom: Dr. Anstrom has received research support from AstraZeneca (significant), Eli Lilly & Company (significant), and Medtronic (significant); has served as a consultant for Abbott Vascular (modest), AstraZeneca (modest), Bristol-Meyers Squibb (modest), Gilead (modest), Pfizer (modest), GSK (modest), Promedior (modest), and Ikaria (modest); and has served on data monitoring committees for NIH (modest), University of North Carolina (modest), University of Miami (modest), Forest (modest), Pfizer (modest), GSK (modest), and Vertex (modest).
CB Granger: Dr. Granger reports research funding from Boehringer Ingelheim, Bristol Myers Squibb, GSK, Medtronic Foundation, Merck & Co., Pfizer, Sanofi-Aventis, Takeda, The Medicines Company, Astra Zeneca, Daiichi Sankyo, Janssen Pharmaceuticals, and Bayer (all significant); consulting or other services (including CME) for Boehringer Ingelheim, Bristol Myers Squibb, GSK, Hoffman-La Roche, Sanofi-Aventis, Takeda, The Medicines Company, Astra Zeneca, Ross Medical Corporation, Janssen Pharmaceuticals, Salix Pharmaceuticals (all modest); consulting or other non-CME services for Boehringer Ingelheim, Eli Lilly, Pfizer, Sanofi-Aventis, Daiichi Sankyo (all modest), and Bristol Myers Squibb (significant).
JP Piccini: Dr. Piccini reports grant funding from ARCA biopharma (>10 k), Boston Scientific (>10 k), Johnson & Johnson (>10 K), GE Healthcare (>10 k), and ResMed (>10 K); consulting for Johnson & Johnson (<10 K), Biosense Webster (<10 K), and Medtronic (<10 K).
EJ Velazquez: Dr. Velazquez reports funding from Novartis (committee, honorarium; >10k); NHLBI (grants; >10k); Ikaria Pharmaceuticals (grants; >10k)
BR Shah: Dr. Shah has no relevant disclosures to report.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Table S1. Unadjusted Post-cardioversion Outcomes by Heart Failure Status