T wave alternans and ventricular arrhythmias in arterial hypertension

Patients with a positive microvolt-level T wave alternans (TWA) are charact erized by an increased risk of ventricular tachyarrhythmias. Arterial hyper tension leads to an increase of sudden cardiac death risk, particularly if left ventricular hypertrophy is present. The aim of this study was to inves tigate the value of TWA in patients with arterial hypertension. Fifty-one c onsecutive patients were included in the study. TWA analysis was performed with patients sitting on a bicycle ergometer and exercising with a gradual increase of workload to maintain a heart rate of at least 105/min. After re cording 254 consecutive low-noise-level heartbeats, the exercise test was s topped. The ECG signals were digitally processed by a spectral analysis met hod. The magnitude of TWA was measured at a frequency of 0.5 cycle per beat . A TWA was defined as positive if the ratio between TWA and noise level wa s >3.0 and the amplitude of the TWA was >1.8 muV. Eight of the 51 patients (16%) showed a positive TWA, If left ventricular hypertrophy was present, t he prevalence of TWA was higher (33.3% versus 8.3%; P<0.05). Sensitivity co ncerning a previous arrhythmic event was 73%, and specificity was 100%. The alternans ratio was significantly higher in patients with a previous event (39.3+/-62.3 versus 2.4+/-4.6; P<0.001), as was the cumulative alternans v oltage (4.7+/-4.1 versus 1.6+/-1.9 muV; P<0.001). In 16 patients invasively investigated by an electrophysiological study, a significant correlation b etween inducibility of tachyarrhythmias and a positive TWA result was found (Spearman R=0.36, P=0.01). We conclude that the arrhythmic risk of patient s with arterial hypertension is markedly increased if microvolt-level TWA i s present. The prevalence of TWA is higher in patients with left ventricula r hypertrophy.