The ventricular ectopic QRS interval (VEQSI): Diagnosis of arrhythmogenic right ventricular cardiomyopathy in patients with incomplete disease expression

Background The ventricular ectopic QRS interval (VEQSI) has been shown to identify structural heart disease and predict mortality. In arrhythmogenic right ventricular cardiomyopathy (ARVC), early diagnosis is difficult using current methods, and life-threatening arrhythmias are common and difficult to predict. Objective The purpose of this study was to assess the utility of ventricular ectopic indices including VEQSI in ARVC diagnosis. Methods We studied 70 patients with ARVC [30 with definite disease (age 47 ± 12 years; 60% male), 40 with incomplete disease expression (age 44 ± 18 years; 44% male)], 116 healthy controls (age 40 ± 15 years; 56% male), and 26 patients with normal heart right ventricular outflow tract (RVOT) ectopy (age 46 ± 17 years; 27% male). The duration of the broadest ventricular ectopic beat during 12-lead Holter monitoring was recorded as VEQSI max. Results VEQSI max was associated with age and gender, but not with conducted QRS duration. Adjusted VEQSI max was greater in ARVC patients than in control groups. In healthy males (44.5 years), estimated VEQSI max was 163 ms (95% confidence interval [CI] 159-167 ms); in definite ARVC 212 ms (95% CI 206-217 ms); in incompletely expressed ARVC 204 ms (95% CI 199-210 ms); and in normal heart RVOT ectopy 171 ms (95% CI 165-178 ms). VEQSI max >180 ms had 98% sensitivity and specificity for diagnosis of ARVC (area under the curve 0.99, 95% CI 0.980-0.998). In our incompletely expressed ARVC patients, VEQSI max >180 ms identified 88% as affected. Conclusion VEQSI max distinguishes ARVC patients, including those with incomplete disease expression, from healthy controls and patients with normal heart RVOT ectopy.