Abstract 2603: Discrimination of Exercise Induced Ventricular Arrhythmia Morphology and Association with Structural Heart Disease
Introduction: The purpose of this study is to determine if assessment of the QRS morphology of exercise induced ventricular arrhythmia (EIVA) refines identification of underlying heart disease. EIVA has been associated with heart disease, but some EIVA, notably idiopathic right ventricular outflow tract (RVOT) EIVA, can be benign.
Methods: Over 8,000 consecutive patients undergoing exercise stress testing were prospectively evaluated for EIVA. Exercise tracings and medical records from 201 consecutive patients with identified EIVA were available for review and serve as the basis for the cohort under investigation.
Results: Eighty-eight patients (43.8%) had multiple morphologies and 113 (56.2%) had a single morphology of EIVA. Structural heart disease was present in 111 (55.2%) of patients: LVEF <40% (48, 23.9%), LVIDed >5.7cm (47, 23.4%), documented coronary artery disease (49, 24.4%), and greater than mild valvular heart disease (44, 21.9%). Structural heart disease was present in 59 of 92 (64.1%) patients with only right bundle branch block morphology compared to 28 of 66 (42.4%) patients with only left bundle branch block morphology (p=0.009). Of 25 patients with EIVA consistent with RVOT origin, structural heart disease was present in 10 (40.0%) as compared to 101 of 176 (57.4%) of those with other arrhythmia morphologies (p=0.132). EIVA with a structurally normal heart had a shorter coupling interval (381 ± 101 vs. 458 ± 144msec, p<0.0001) and were faster (cycle length 327 ± 117 vs. 368 ± 103msec, p=0.009) than those with structural heart disease.
Conclusions: In patients who have ventricular arrhythmias on exercise testing, RBBB morphology EIVA is usually associated with structural heart disease. Although less common, and subject to referral bias, LBBB outflow tract QRS morphologies consistent with an RVOT origin commonly have underlying structural heart disease and further clinical evaluation may still be warranted. The morphology of EIVA is of limited use in excluding structural heart disease.