Electrocardiographic comparison of ventricular premature complexes during exercise test in patients with CPVT and healthy subjects.

ABSTRACT

BACKGROUND: Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a rare but highly malignant inherited arrhythmic disorder. Although a standardized exercise stress test (ST) is the most reliable way to diagnose CPVT, in 30% only single ventricular premature beats (VPCs) were recorded. OBJECTIVE: To evaluate whether electrocardiographic characteristics of VPCs during ST distinguish patients with CPVT from healthy subjects. METHODS: Electrocardiographic characteristics of VPCs during ST in 16 calsequestrin-2 (CASQ2) mutation carriers CPVT patients were compared with that in 36 healthy subjects. RESULTS: CPVT patients had more VPCs (31 ± 14 vs 3 ± 4, P < 0.0001), longer QRS duration (139 ± 18 ms vs 121 ± 21, P = 0.004), and coupling interval (CI; 476 ± 58 ms vs 355 ± 61 ms, P < 0.0001). The most sensitive characteristics for CPVT were >10 VPCs/test (100% sensitivity, 100% negative predictive value [NPV]), left bundle branch block (LBBB) pattern with inferior axis (88% sensitivity, 94% NPV), and CI longer than 400 ms (88% sensitivity, 94% NPV). Bigeminy or trigeminy or LBBB pattern with inferior axis was most specific for CPVT at 100% (100% positive predictive value PPV, 92% NPV). First VPC during the recovery period and VPC recording more than 1 minute during the recovery period were most specific for healthy subjects (100% specificity, 100% PPV). In multivariate analysis, QRS duration >120 ms (odds ratio 4.2, 95% confidence interval 1-17.6, P = 0.04) and first VPC at ≥10 mets (odds ratio 9.1, 95% confidence interval 2.01-41.1, P = 0.004) each predicted the presence of CPVT. CONCLUSIONS: Several electrocardiographic criteria can help distinguish VPCs originating from CPVT compared with healthy subjects.