RESUMEN
BACKGROUND: Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inheritable cardiac disease predisposing to malignant ventricular arrhythmias. OBJECTIVE: We aimed to explore the incidence and severity of ventricular arrhythmias in patients with CPVT before the initiation of ß-blocker treatment, when treated with ß1-selective ß-blockers, and when treated with nadolol. METHODS: In this study, 34 patients with CPVT were included (mean age 34 ± 19 years; 15 (44%) women; 30 (88%) ryanodine receptor 2 variant positive). We performed 3 bicycle exercise stress tests in each patient: (1) before the initiation of ß-blocker treatment, (2) after >6 weeks of treatment with ß1-selective ß-blockers and (3) after >6 weeks of treatment with nadolol. We recorded resting and maximum heart rates and the most severe ventricular arrhythmia occurring. Severity of arrhythmias was scored as 1 point for no arrhythmias or only single ventricular extrasystoles, 2 points for >10 ventricular extrasystoles per minute or bigeminy, 3 points for couplets, and 4 points for nonsustained ventricular tachycardia or sustained ventricular tachycardia. RESULTS: Resting heart rate was similar during treatment with nadolol and ß1-selective ß-blockers (54 ± 10 beats/min vs 56 ± 14 beats/min; P = .50), while maximum heart rate was lower during treatment with nadolol compared with ß1-selective ß-blockers (122 ± 21 beats/min vs 139 ± 24 beats/min; P = .001). Arrhythmias during exercise stress testing were less severe during treatment with nadolol compared with during treatment with ß1-selective ß-blockers (arrhythmic score 1.6 ± 0.9 vs 2.5 ± 0.8; P < .001) and before the initiation of ß-blocker treatment (arrhythmic score 1.6 ± 0.9 vs 2.7 ± 0.9; P = .001); however, no differences were observed during treatment with ß1-selective ß-blockers compared with before the initiation of ß-blocker treatment (arrhythmic score 2.5 ± 0.8 vs 2.7 ± 0.9; P = .46). CONCLUSION: The incidence and severity of ventricular arrhythmias decreased during treatment with nadolol compared with during treatment with ß1-selective ß-blockers. ß1-Selective ß-blockers did not change the occurrence or severity of arrhythmias compared with no medication.