Direct Current Cardioversion of Atrial Arrhythmias in Adults With Cardiac Amyloidosis

Abstract

Background: Arrhythmias, conduction abnormalities, and intracardiac thrombus are common in patients with cardiac amyloidosis (CA). Outcomes of direct-current cardioversion (DCCV) for atrial arrhythmias in patients with CA are unknown.

Objectives: This study sought to examine DCCV procedural outcomes in patients with CA.

Methods: Patients with CA scheduled for DCCV for atrial arrhythmias from January 2000 through December 2012 were identified and matched 2:1 with control patients by age, sex, type of atrial arrhythmia, and date of DCCV.

Results: CA patients (n = 58, mean age 69 ± 9 years, 81% male) were included. CA patients had a significantly higher cardioversion cancellation rate (28% vs. 7%; p < 0.001) compared with control patients, mainly due to intracardiac thrombus identified on transesophageal echocardiogram (13 of 16 [81%] vs. 2 of 8 [25%]; p = 0.02); 4 of 13 of the CA patients (31%) with intracardiac thrombus on transesophageal echocardiogram received adequate anticoagulation ≥3 weeks and another 2 of 13 (15%) had arrhythmia duration <48 h. DCCV success rate (90% vs. 94%; p = 0.4) was not different. Procedural complications were more frequent in CA versus control patients (6 of 42 [14%] vs. 2 of 106 [2%]; p = 0.007); complications in CA included ventricular arrhythmias in 2 and severe bradyarrhythmias requiring pacemaker implantation in 2. The only complication in the control group was self-limited bradyarrhythmias.

Conclusions: Patients with CA undergoing DCCV had a significantly high cancellation rate mainly due to a high incidence of intracardiac thrombus even among patients who received adequate anticoagulation. Although the success rate of restoring sinus rhythm was high, tachyarrhythmias and bradyarrhythmias complicating DCCV were significantly more frequent in CA patients compared with control patients.

Keywords: atrial arrhythmia; atrial fibrillation; cardiac amyloidosis; cardioversion; intracardiac thrombus; transesophageal echocardiogram.

FIGURE 1. Rate of Atrial Arrhythmia Recurrence Following Successful DCCV in Patients With CA Compared With Control Patients

This Kaplan-Meier curve shows that the rate of atrial arrhythmia recurrence at 1 year following successful direct-current cardioversion (DCCV) is not different in patients with cardiac amyloidosis (CA) compared with control patients (48% vs. 55%; p = 0.75). Thirty-eight CA patients underwent successful cardioversion; within 1 year, 16 patients had documented recurrences, 6 died, 14 patients had no documented recurrence, and the status of recurrence was unknown in 2 patients. On the other hand, 100 control patients underwent successful cardioversion; within 1 year, 52 patients had documented recurrences, 4 died, 40 had no documented recurrence, and the status of recurrence was unknown in 4 patients.

CENTRAL ILLUSTRATION. Cardioversion in Cardiac Amyloidosis Outcomes

Transesophageal and direct-current cardioversion procedural outcomes (A) and reasons for cancelling planned cardioversion (B) in patients with cardiac amyloidosis (CA) compared with control patients (*p 0.05 cases vs. control patients) (A). This bar graph summarizes direct-current cardioversion procedural outcomes in patients with CA compared with control patients. The CA group had a significantly higher cardioversion cancellation rate (16 of 58 [28%] vs. 8 of 114 [7%]; p < 0.001) compared with control patients. Among the patients who proceeded to DCCV (CA n = 42; control patients n = 106), the success rate (38 of 42 [90%] vs. 100 of 106 [94%]; p = 0.47) was not different between the 2 groups. However, the procedural complication rate was significantly higher in CA versus control patients (6 of 42 [14%] vs. 2 of 106 [2%]; p = 0.007). (B) The 2 pie charts summarize the reasons for cancelling planned cardioversion in the CA cases and control patients. The main reasons for cancellation were intracardiac thrombus identified on transesophageal echocardiogram (CA 13 of 16 [81%] vs. control patients 2 of 8 [25%]; p = 0.02) and spontaneous cardioversion (CA 2 of 16 [13%] vs. control patients 5 of 8 [63%]; p = 0.02). Of the 13 CA patients with intracardiac thrombus, 2 had atrial fibrillation <48 h, and 4 had a therapeutic international normalized ratio for ≥3 weeks before transesophageal echocardiogram.