Inappropriate shocks in patients receiving internal cardioverter-defibrillators for malignant ventricular arrhythmias.

Implantation of internal cardioverter defibrillators (ICDs) for treatment of malignant ventricular arrhythmias is complicated by failure of therapy or inappropriate shocks. We studied 81 patients (age range 16-72 years; mean 48 +/- 13 years) who underwent ICD implantation for device therapy. The underlying aetiology was ischaemic heart disease (39%), cardiomyopathies (32%) and others (28%). Information regarding shocks was collected using Holter monitoring, telemetry or device memory (stored electrograms) and lastly by clinical follow-up. Fifty-eight patients completed 36 months of follow-up. Thirty-five patients experienced 337 spontaneous shocks, appropriate in 21, inappropriate in 12, and both in two patients. Of the 74 episodes of inappropriate discharges for rhythms other that ventricular tachycardia (VT) or ventricular fibrillation(VF), 55 percent were due to supraventricular arrhythmias (atrial flutter or fibrillation). Lead malfunction occurred in four and the device was replaced in two. Additional drugs controlled AF in one. There was no mortality in any of the 81 patients. The frequency of shocks was highest in the first six months after implantation and atrial fibrillation remains the main cause. In conclusion, inappropriate shocks are frequent in patients undergoing ICD implantation.

Correlation of 12 lead ECG QRS score with severity of aortic stenosis.

The hemodynamic data and electrocardiograms of thirty-three patients of moderate to severe aortic stenosis were analysed retrospectively to find out if there was any correlation between 12 lead ECG-QRS score and left ventricular peak systolic pressure (LVPSP) and/or peak systolic gradient (PSG) across the aortic valve. The mean age of the study population was 33.33 (+/- 15.02SD) years, with the male to female ratio being 9:2. The mean 12 lead ECG-QRS score in these 33 patients was 281 mm (+/- 46.02SD), the mean LVPSP 203.52 mmHg (+/- 46.62SD) and the mean PSG across the aortic valve was 81.0 mmHg (+/- 41.62SD). There was good correlation of 12 lead ECG-QRS score with LVPSP (r = 0.47, P less than 0.001) and with PSG across the aortic valve (r = 0.58, P less than 0.001), latter being more significant. The best correlation was however found between 12 lead ECG-QRS score and PSG across the aortic valve in patients over 35 years of age (r = 0.88). In conclusion there is a direct relationship between 12 lead ECG-QRS score and peak systolic gradient across the aortic valve and the latter can be approximately calculated non-invasively with the help of regression equation- Peak systolic gradient (in mmHg) = 12 lead ECG-QRS score/3 - 10.6