Interventricular difference of electrocardiographic repolarization times in patients with arrhythmogenic right ventricular dysplasia

Abstract

Experimental studies show longer action potential durations in left (LV) than in right ventricle (RV). Electrocardiographic (ECG) repolarization times may be longer in RV than in LV in patients with arrhythmogenic right ventricular dysplasia (ARVD). We measured beat-to-beat QT intervals at rest and during Valsalva maneuver from 25 ECG leads over anterior chest in 9 ARVD patients (age 53±7) and 9 healthy controls (44±10). The arithmetic difference between LV and RV type leads (LV–RV) according to QRS morphology was defined to represent ECG interventricular repolarization gradient. T-peak to T-end (TPE) intervals defined ECG transmural dispersion of repolarization. All 9 control subjects expectedly had longer baseline QT intervals in LV than RV whereas 6 out of 9 ARVD patients had longer QT intervals in RV. QT difference LV–RV was 7±5 ms in controls and −5±13 ms in ARVD (P<0.05). ARVD patients had also longer TPE intervals in RV than LV (73±9 vs. 67±8 ms, P<0.01), whereas controls showed opposite trend (64±7 vs. 68±7 ms, P=0.10). During Valsalva-strain, ARVD patients showed exaggerated QT shortening in RV, increasing QT difference LV–RV to 4±20 ms (P<0.02 vs. rest) whereas controls tended to decrease LV–RV. ARVD patients show ECG interventricular repolarization gradient from RV to LV and increased ECG transmural dispersion of repolarization in RV. Valsalva-strain temporarily reverses the interventricular repolarization gradient in ARVD patients. The abnormal and deranged response of ECG interventricular repolarization gradient to volume/pressure changes in diseased RV may create substrate for arrhythmias in ARVD.