The inverse relationship between baseline left ventricular ejection fraction and outcome of antiarrhythmic therapy: A dangerous imbalance in the risk-benefit ratio

Each year, millions of prescriptions are written for antiarrhythmic drug suppression of ventricular arrhythmias. A large portion of these prescriptions are written for patients with asymptomatic, complex ventricular arrhythmias and organic heart disease, termed "potentially malignant" or "potentially lethal." Since arrhythmia suppression in this population is of unproven benefit, we performed the following study: A total of 246 patients (42% with significant left ventricular dysfunction) had complex ventricular arrhythmias, and were treated with one of eight antiarrhythmic drugs (Vaughan Williams classes IA, IB, IC, II, and III). The extent of arrhythmia suppression and the development of serious complications resulting from therapy after 2 weeks was of primary interest. A total of 82 of 246 (33%) maintained adequate (protocol definition) suppression of both ventricular premature beats (VPBs) as well as nonsustained ventricular tachycardia (VT) for 2 weeks, mostly in patients with left ventricular ejection fraction (LVEF) ≥40% (p = 0.04 versus LVEF <40%). Life-threatening complications of antiarrhythmic therapy occurred most frequently in the 61 patients with an LVEF <30% compared to the 185 patients with LVEF ≥30% (15% versus 2.1%, p = 0.0005). Suppression of VT was achieved nearly twice as commonly in patients with an LVEF ≥30% than in those with an LVEF <30% (67% versus 36%; p = 0.0008). Life-threatening complications occurred seven times as frequently in patients presenting with nonsustained VT and an LVEF <30% (18% versus 2.3%; p = 0.003). Thus, analysis of our data suggests that in patients with low LVEF and "potentially malignant" ventricular arrhythmia, suppression is often not maintained even for 2 weeks, is of questionable benefit, and is unfortunately "potentially lethal." Until this treatment strategy is shown to improve prognosis, the risk is substantial and arrhythmia suppression in this population is not warranted.