ASSESSMENT OF LATE POTENTIALS IN PATIENTS WITH ESSENTIAL-HYPERTENSIONBY THE SIGNAL-AVERAGED ELECTROCARDIOGRAM WITH 5-YEAR FOLLOW-UP

Both the Framingham and Manitoba Heart Studies have identified electro cardiographic left ventricular (LV) hypertrophy (LVH) as a risk factor for sudden cardiac death. Low amplitude ventricular late potentials i n the terminal part of ventricular activation have been associated wit h sustained ventricular tachycardia and have identified those at risk for sudden cardiac death. Therefore, we prospectively examined 23 esse ntial hypertensives without known symptomatic coronary heart disease b y two-dimensional echocardiography and signal averaged electrocardiogr ams (SAECGs) for the detection of ventricular late potentials. The SAE CG vector-magnitude complex measurements included the total duration o f the complex (QRSd), the voltage in the last 40 ms (V40), and the dur ation of low amplitude signals < 40 muV in the terminal portion of the complex (LASd). Echocardiographic parameter means were: LV diastolic diameter = 46.0 +/- 4.5 mm, combined septal and posterior wall thickne ss = 23.3 +/- 4.2 mm, LV mass (Woythaler method) = 235.1 +/- 69.1 g, L V mass (Penn method) = 199.5 +/- 55.3 g and ejection fraction = 63.9 /- 6.2%. SAECG measurement means were QRSd = 88.2 +/- 9.9 ms, V40 = 63 .1 +/- 34.7 muV RMS, and LASd = 23.5 +/- 10.0 ms. No echocardiographic parameter correlated with SAECG duration; however, age correlated wit h QRSd (r = 0.48, P = 0.02). Posterior wall thickness (r = -0.43, P = 0.04), LV mass index (r = -0.44, P = 0.03) and LV mass//height (r = -0 .49, P = 0.02) inversely correlated with LASd. Only three patients had ventricular late potentials and none had an increased LV index by ech ocardiography or significant ventricular ectopy by ambulatory ECG. All 23 patients were alive with no known arrhythmic event after five year s; one patient developed unstable angina requiring angioplasty. The ro le of the SAECG in hypertensive patients remains to be defined.