Sympathetic blockade with esmolol significantly reduced the amplitude of T-wave alternans and decreased the number of positive TWA tests from 70% to 35% (P<0.05).
Does selective autonomic blockade alter T-wave alternans in high-risk patients with coronary artery disease and left ventricular dysfunction?
Sympathetic blockade with esmolol significantly reduces T-wave alternans in high-risk patients, providing a potential mechanism for the reduction in sudden cardiac death conferred by beta-blockers.
Absolute Event Rate: 35% vs 70%
p-value: p=<0.05
BACKGROUND: T-wave alternans (TWA) is an important noninvasive measure of ventricular arrhythmia vulnerability. This study tested the hypothesis that the autonomic nervous system influences TWA measurement in high-risk subjects with coronary artery disease. METHODS AND RESULTS: T-wave alternans was measured in 60 patients with coronary artery disease, left ventricular dysfunction, and inducible sustained ventricular tachycardia during electrophysiological studies. All patients had TWA measured at baseline with atrial pacing at 100 bpm (600 ms), 109 bpm (550 ms), and 120 bpm (500 ms). After a 10-minute recovery period, TWA was measured again after sympathetic blockade (esmolol, n=20), parasympathetic blockade (atropine, n=20), or no intervention (control subjects, n=20). The prevalence of significant TWA was unchanged compared with baseline after atropine infusion and in the control group. In contrast, the amplitude of TWA in the vector magnitude lead was significantly reduced after esmolol infusion (P<0.001), and the number of positive TWA tests was reduced by 50% (70% versus 35%, P<0.05). CONCLUSIONS: Our findings have important implications for the use of TWA to risk-stratify patients for life-threatening ventricular arrhythmias and provide a new potential mechanism for the reduction in sudden cardiac death conferred by beta-blockers among patients with coronary artery disease and congestive heart failure.
Rashba et al. (Tue,) conducted a other in Coronary artery disease with left ventricular dysfunction and inducible sustained ventricular tachycardia (n=60). Esmolol (sympathetic blockade) or Atropine (parasympathetic blockade) vs. No intervention was evaluated on Positive T-wave alternans tests (p=<0.05). Sympathetic blockade with esmolol significantly reduced the amplitude of T-wave alternans and decreased the number of positive TWA tests from 70% to 35% (P<0.05).