OBJECTIVES: We compared amiodrone, sotalol with β-blocker for prevention of inappropriate implantable cardioverter-defibrillator (ICD) shocks in patients with risk of inappropriate shock.
BACKGROUND: It has been shown that patients with atrial fibrillation (AF) or congestive heart failure (CHF) are more vulnerable to inappropriate shocks. The effects of antiarrhythmic drugs in these patients with high risk of inappropriate shocks remain unknown.
METHODS: From April 1996 to February 2006, 137 patients received ICD implantation at Asan Medical Center. Fifty five of them had a history of AF or NYHA class ≥Ⅲ, and were divided into three groups (amiodarone group: n=24, sotalol group: n=12, β-blocker: n=19). Primary outcome was inappropriate ICD shock for supraventricular tachycardia or AF.
RESULTS: The demographic and clinical features among the groups were not significantly different. Inappropriate shock occurred in 3 patients (12.5%) in amiodarone group, 5 patients (41.7%) in sotalol group and 10 patients (52.6%) in β-blocker group. The 4-year rates of inappropriate shocks were 27.3% in amiodarone group, 54.3% in sotalol group, 70.6% in β-blocker group (amiodarone vs β-blocker: Log-rank p=0.003, sotalol vs β-blocker: Log-rank p=0.16, amiodarone vs sotalol: Log-rank p=0.29). Amiodarone significantly reduced the risk of inappropriate shock compared with β-blocker (HR, 0.17; 95% CI, 0.05-0.64; p=0.008). However, sotalol did not decreased the risk of inappropriate shock compared with β-blocker (HR, 0.57; 95% CI, 0.19-1.68; p=0.3). Eight patients (33.3%) discontinued amiodarone due to pulmonary or thyroid toxicity.
CONCLUSIONS: Amiodarone is effective for preventing inappropriate shock in patients with AF or CHF. However, it has a significant risk of drug-related adverse effects.
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