Background: Idiopathic verapamil-responsive left ventricular tachycardia (IVRLVT) is a rare, well known form of ventricular tachycardia. Issues concerning long-term prognosis, drug prophylaxis and non-pharmacological therapy are rarely reported in the literature. We report the long-term follow-up, the efficacy of various drugs in the prophylaxis and the role of catheter ablation in a large group of patients with IVRLVT.
Methods and results: This retrospective study involves 37 patients with a mean age of 28.3 +/- 14.8 years at first IVRLVT episode. The tachycardia morphology was typically with a right bundle-branch block configuration in all cases, with left axis deviation in 33 and right axis deviation in 5 (one patient had the 2 morphologies). Four patients had a mitral valve prolapse; the remaining 33 patients had neither clinical nor echocardiographic signs of heart disease. Only sporadic ventricular extrasystoles were detected at Holter monitoring in 73% of cases; 30% of patients had positive criteria for the presence of late potentials at signal averaged ECG. During electrophysiologic study, the tachycardia could be easily induced in 91% of patients. Mean follow-up is 7.3 +/- 4.7 years; all patients are alive at the end of follow-up. A mean of 2.3 +/- 1.2 drugs was prescribed in 35 patients (94.6%); betablockers were effective in 66% of the cases, verapamil in 20%, class I drugs in 22%, class III drugs in 15%. Both the 2 patients, who never received prophylaxis, and the 4 who stopped medication, utilize verapamil in case of recurrences. Eight patients were submitted to catheter ablation, with DC shock the first 2 patients, with RF energy from the third on; all but one (with DC shock) were successfully cured.
Conclusions: Long-term follow-up confirmed the good prognosis of this form of ventricular tachycardia; a new insight that has been addressed about prophylaxis is the high efficacy of betablockers in preventing relapse and the poor efficacy of verapamil per os in chronic prophylaxis. Radiofrequency catheter ablation is effective and safe, using the earliest ventricular potential and the pace-mapping reproducing the same morphology of the tachycardia in all the 12 leads as a marker to identify the site of RF application, and may be proposed to all patients suffering from frequent episodes of IVRLVT.