QT-INTERVAL VARIABILITY IN HYPERTROPHIC CARDIOMYOPATHY PATIENTS WITH CARDIAC-ARREST

We studied long-term variability of QT-dispersion in three patients wi th hypertrophic cardiomyopathy (Maron III) and ventricular fibrillatio n. Late potentials were absent on signal-averaged electrocardiogram. S T-segment depression was recorded in all three patients at Holter moni toring, and in two during exercise stress testing, nonsustained ventri cular tachycardia was present in only one patient. The maximal correct QT-interval and corrected QT-dispersion (QT(cd)) were measured retros pectively, both off-drug and under treatment with amiodarone and beta- blocker (two patients), or sotalol alone (one patient). Ten age- and s ex-matched normal subjects, and 13 hypertrophic cardiomyopathy patient s without ventricular arrhythmias formed the control groups. QT(cd)-va lues in the control groups never exceeded 80 ms and mean values of 30. 1 +/- 10.1 ms and 44.1 +/- 7.9 ms respectively, were found. During lon g-term follow-up, QT(cd) increased progressively in two of the three p atients with ventricular fibrillation, and at the time of the event al l showed a value > 100 ms. Sotalol, but not the amiodarone reduced QT( cd). QT(cd) seems to be a powerful predictor of ventricular electrical instability in the absence of other specific markers, and a promising guide for effective pharmacological therapy.