Electrical and mechanical interventricular dyssynchrony coupling in patients with bradycardia: A UHF-ECG validation trial

BACKGROUND: Ultra-high-frequency electrocardiography (UHF-ECG) is a noninvasive tool visualizing the ventricular activation sequence. It was never compared with other methods of dyssynchrony assessment in patients with bradycardia. OBJECTIVE: We aimed to compare UHF-ECG interventricular electrical dyssynchrony (e-DYS) with interventricular mechanical dyssynchrony (IVMD) measured by echocardiography in patients receiving right ventricular pacing (RVP) or conduction system pacing (CSP). METHODS: Fifty-three patients with advanced atrioventricular conduction disease and preserved ventricular systolic function were prospectively assigned to RVP (n=32) or CSP (n=21). IVMD was measured as the time difference between left ventricular and right ventricular preejection periods. Interventricular e-DYS was calculated by software as the time difference between activation in V and V chest electrodes using UHF-ECG. RESULTS: The median age of patients was 75 (interquartile range 72-80) years, and both groups had similar clinical characteristics. Baseline IVMD and interventricular e-DYS were similar in the entire population (-2 [-8 to 5] ms vs-1 [-6 to 5] ms, respectively; P=.52). Both methods showed the same dyssynchrony trends after pacemaker implantation; that is, while both IVMD and interventricular e-DYS increased in the RVP group (IVMD 28 [23-33] ms vs interventricular e-DYS 26 [19-33] ms; P=.99), they remained low in the CSP group (IVMD -7 [-16 to 2] ms vs interventricular e-DYS -5 [-12 to 2] ms; P=.91). There was a moderate overall correlation between IVMD and interventricular e-DYS for all studied ventricular rhythms (R=0.74). CONCLUSION: UHF-ECG noninvasively expresses interventricular dyssynchrony from V -V chest leads with similar results to echocardiography. RVP increases interventricular dyssynchrony, while CSP preserves synchronous ventricular activation.