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QT-interval variability in hypertrophic cardiomyopathy patients with cardiac arrest
M Miorelli1, G Buja, P Melacini
1Department of Cardiology, University of Padua, Italy.
Insights
Corrected QT-dispersion (QTcd) predicts ventricular electrical instability in hypertrophic cardiomyopathy. Elevated QTcd values (>100 ms) were observed before ventricular fibrillation events, with sotalol showing efficacy in reducing QTcd.
Area of Science:
- Cardiology
- Electrophysiology
- Pharmacology
Background:
- Hypertrophic cardiomyopathy (HCM) poses risks for ventricular arrhythmias.
- Assessing long-term electrical instability in HCM is crucial for risk stratification.
- Traditional markers like late potentials and non-sustained ventricular tachycardia may be absent.
Observation:
- Three HCM patients (Maron III) with ventricular fibrillation were studied.
- Signal-averaged ECG showed no late potentials; ST depression was common.
- Corrected QT-dispersion (QTcd) was measured long-term, off-drug and during treatment.
Findings:
- QTcd progressively increased in two patients prior to ventricular fibrillation.
- All patients exhibited QTcd > 100 ms at the time of ventricular fibrillation.
- Sotalol effectively reduced QTcd, while amiodarone did not show significant reduction.
Implications:
- QTcd serves as a potent predictor of ventricular electrical instability in HCM.
- QTcd can guide effective pharmacological therapy selection for HCM patients.
- Monitoring QTcd offers a promising approach for managing arrhythmia risk in HCM.
Abstract:
We studied long-term variability of QT-dispersion in three patients with hypertrophic cardiomyopathy (Maron III) and ventricular fibrillation. Late potentials were absent on signal-averaged electrocardiogram. ST-segment depression was recorded in all three patients at Holter monitoring, and in two during exercise stress testing, nonsustained ventricular tachycardia was present in only one patient. The maximal correct QT-interval and corrected QT-dispersion (QTcd) were measured retrospectively, both off-drug and under treatment with amiodarone and beta-blocker (two patients), or sotalol alone (one patient). Ten age- and sex-matched normal subjects, and 13 hypertrophic cardiomyopathy patients without ventricular arrhythmias formed the control groups. QTcd-values 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 long-term follow-up, QTcd increased progressively in two of the three patients with ventricular fibrillation, and at the time of the event all showed a value > 100 ms. Sotalol, but not the amiodarone reduced QTcd. QTcd 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.