Relation Between Exercise-Induced Myocardial Ischemia as Assessed by Nitrogen-1 3 Ammonia Positron Emission Tomography and QT Interval Behavior in Patients With Right Bundle Branch Block

Abstract Exercise-induced myocardial ischemia is difficult to detect with ST-T changes in patients with right bundle branch block (RBBB). We sought to predict exercise-induced myocardial ischemia with QT interval behavior during exercise in patients with RBBB. Twenty-two patients with angiographically proven coronary artery disease and RBBB and 9 healthy volunteers underwent nitrogen-13 ammonia positron emission tomography with bicycle ergometer exercise at a fixed workload of 25 W. Regional myocardial blood flow (RMBF) and electrocardiographic changes were measured both at rest and after 5 minutes of exercise. The QT interval was measured from the onset of the QRS complex to the offset of the T wave in lead V 5 . The ΔQT and ΔRMBF, which indicated values after 5 minutes of exercise minus values at rest, were negatively correlated (r = −0.74, p