1027-39 Electrical Alternans During Rest and Exercise as Predictors of Vulnerability to Ventricular Arrhythmias

Abstract

Electrical alternans (ALT) representing visually inapparent beat-to-beat alternating amplitude on the electrocardiogram, has been reported topredict vulnerabilityto ventricular arrhythmias during atrial (A) pacing. We hypothesized that ALT recorded during sinus rhythm and with the heart rate elevated by exercise (Ex) would be similarly predictive. In the pilot phase of a multicenter study, ALT recordings were made at rest, during a bicycle protocol to maintain the heart rate 100–110 bpm, and analyzed using a spectral method incorporating noise reduction software. Ventricular vulnerability was defined by prior episodes of clinical VT or VF or by VT or VF induction at EPS. Sensitivity Specificity +PV -PV RR p Rest 50% 91% 80% 71% 2.8 0.14 Ex 80% 91% 89% 84% 5.3 0.005 Rest/Ex 100% 91% 91% 100% >10 <0.005 +PV: positive predictive value; -PV: negative predictive value; RR: relative risk; p: significance level ALT can be measured during exercise and is an accurate predictor of vulnerability to ventricular arrhythmias. ALT measured during sinus rhythm at rest is not as accurate a predictor. Combining rest and Ex ALT results is more predictive of arrhythmia vulnerability than rest or Ex results alone.