Left Atrial Passive Emptying Function During Dobutamine Stress MR Imaging Is a Predictor of Cardiac Events in Patients With Suspected Myocardial Ischemia

OBJECTIVES The aim of this study was to determine the prognostic value of assessing left atrial function during dobutamine stress testing. BACKGROUND Left ventricular diastolic dysfunction precedes systolic wall motion abnormalities in the ischemic cascade. Severity of left ventricular diastolic function during cardiac stress is not characterized well by current clinical imaging protocols but may be an important prognostic factor. We hypothesized that abnormal early left atrial emptying measured during dobutamine stress cardiac magnetic resonance will reflect these diastolic changes and may be associated with cardiovascular outcomes. METHODS We enrolled 122 consecutive patients referred for dobutamine stress cardiac magnetic resonance for suspected myocardial ischemia. Left atrial volumes were retrospectively measured by the biplane area-length method at left ventricular end-systole (VOLmax) and before atrial contraction (VOLbac). Left atrial passive emptying fraction defined by (VOLmax - VOLbac) X 100%/VOLmax and the absolute percent increase in left atrial passive emptying fraction during dobutamine stress (Delta LAPEF) were quantified. RESULTS Twenty-nine major adverse cardiac events (MACE) occurred during follow-up (median 23 months). By Kaplan-Meier analysis, patients with Delta LAPEF <10.8 (median) experienced higher incidence of MACE than did patients with a Delta LAPEF >10.8 (p = 0.004). By univariable analysis, Delta LAPEF was strongly associated with MACE (unadjusted hazard ratio for every 10% decrease = 1.56, p < 0.005). By multivariable analysis, every 10% decrease in Delta LAPEF carried a 57% increase in MACE, after adjustment to presence of myocardial ischemia and infarction. CONCLUSIONS Reduced augmentation of left atrial passive emptying fraction during dobutamine stress demonstrated strong association with MACE. We speculate that reduced left atrial passive emptying reserve during inotropic stress may represent underlying diastolic dysfunction and warrants further investigation. (J Am Coll Cardiol Img 2011;4:378-88) (C) 2011 by the American College of Cardiology Foundation