Differentiating arrhythmogenic right ventricular cardiomyopathy from right ventricular outflow tract ventricular tachycardia using multilead QRS duration and axis.

BACKGROUND: Ventricular tachycardia (VT) resulting from arrhythmogenic right ventricular cardiomyopathy (ARVC) may be difficult to differentiate from idiopathic right ventricular outflow tract (RVOT) VT.
OBJECTIVES: The purpose of this study was to investigate the hypothesis that QRS characteristics would be different in ARVC because of altered conduction through abnormal myocardium.
METHODS: In 24 RVOT VT patients (18 women and 6 men; age 42 +/- 10 years) and 20 ARVC patients (12 women and 8 men; age 38 +/- 14 years), mean QRS duration, frontal plane axis, and precordial R-wave transition were measured in 12-lead ECGs recorded during VT.
RESULTS: Mean QRS duration was longer in all 12 leads in ARVC patients. A significant difference was noted in leads I, III, aVL, aVF, V(1), V(2), and V(3) (P <.05). Leads I and aVL had the largest mean difference between ARVC and RVOT VT patients of 17.6 +/- 4.7 ms and 15.8 +/- 7.5 ms, respectively (P <.0001). Lead I QRS duration > or =120 ms had a sensitivity of 100%, specificity 46%, positive predictive value 61%, and negative predictive value 100% for ARVC. The area under the receiver operating characteristic (ROC) curve was 0.89. The addition of mean QRS axis <30 degrees (R<S in lead III) to the above criterion increased specificity for ARVC to 100%. QRS duration remained sensitive and specific in the subgroup of nine ARVC ECGs with an inferior axis (ROC area 0.82). R-wave transition was not different between groups.
CONCLUSION: QRS duration is longer in ARVC compared with RVOT VT. An algorithm combining lead I QRS duration for sensitivity and axis for specificity is useful for differentiating the two tachycardia substrates.