Second coupling interval to distinguish malignant from benign ventricular tachycardia from right ventricular outflow tract

Purpose: Idiopathic ventricular tachycardia (VT) originating from the right ventricular outflow tract (RVOT) in patients without structural heart diseases are usually considered a benign condition. In some rare malignant cases, patients suffer from syncope or sudden cardiac death. They are frequently preceded by non-sustained VT (NSVT). We aimed to clarify the ECG characteristics of these NSVTs that could differentiate malignant from benign RVOT VT. Methods: We retrospectively evaluated the patients without structural heart disease who had documented RVOT VT on ECG. The ECG parameters were compared between 24 patients with syncope, aborted sudden cardiac death or VF (malignant group) and 21 patients with monomorphic VT without syncope (benign group). Results: The coupling interval (CI) of the first VT beat was comparable between the malignant and benign groups (457±77 ms vs. 479±76 ms; P=0.340). The second CI of VT beats was significantly shorter in the malignant group than that of the benign group (316±55 ms vs. 399±82 ms; P<0.001). In the malignant group, the cycle length of VT was shorter than that of the begin group (272±40 ms vs. 354±90 ms; P=0.001). Immediate success rate of catheter ablation was 62% in the malignant group and 95% in the benign group (P=0.002). The VTs in the malignant group frequently showed more than one focus, while the majority of the VTs in benign group showed single focus of VT (1.81 vs. 1.10; P=0.014). Conclusions: The shorter second CI and TCL of NSVT may result in malignant RVOT VTs. Malignant RVOT VT had frequently multiple foci of VT and lower success rate of catheter ablation. Our data suggest that careful measurement of CI and TCL of NSVT may help to distinguish malignant RVOT VT to give active treatment for prevention of future cardiac events.