Arrhythmias and Conduction DisturbancesElectrical Alternans During Rest and Exercise as Predictors of Vulnerability to Ventricular Arrhythmias☆
Section snippets
Study Design:
All patients referred for invasive cardiac electrophysiologic evaluation for syncope, ventricular tachycardia, or fibrillation were eligible for this multicenter study. Patients were excluded if they were unable to complete a bicycle exercise protocol with an elevation of heart rate >100 beats/min or if they had excessive premature ventricular complexes (10%), atrial fibrillation, or a permanent pacemaker. Electrical alternans was successfully measured in 27 patients meeting these entry
Results
The characteristics of the 27 study patients are summarized in Table I. The 20 men and 7 women were an average age of 49 ± 19 years (mean ± SD). Coronary artery disease was present in 11, right ventricular dysplasia in 4, idiopathic-dilated cardiomyopathy in 5, and no structural heart disease in 7.
Discussion
Before the present study it was not known if microvolt level electrical alternans could be reliably measured during sinus rhythm with elevation of the heart rate with exercise or whether such measurements would be predictive of susceptibility to ventricular arrhythmias. Furthermore, it was not known whether the motion artifact of bicycle exercise would preclude the measurement of microvolt level electrical alternans during such exercise. The data in the present study indicate that
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This study was supported by Grant #NAGN-3927 from the National Aeronautics and Space Administration.