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 (VOL(max)) and before atrial contraction (VOL(bac)). Left atrial passive emptying fraction defined by (VOL(max) - VOL(bac)) × 100%/VOL(max) and the absolute percent increase in left atrial passive emptying fraction during dobutamine stress (ΔLAPEF) were quantified.

RESULTS

Twenty-nine major adverse cardiac events (MACE) occurred during follow-up (median 23 months). By Kaplan-Meier analysis, patients with ΔLAPEF <10.8 (median) experienced higher incidence of MACE than did patients with a ΔLAPEF >10.8 (p = 0.004). By univariable analysis, ΔLAPEF was strongly associated with MACE (unadjusted hazard ratio for every 10% decrease = 1.56, p < 0.005). By multivariable analysis, every 10% decrease in ΔLAPEF 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.