Incremental value of three-dimensional echocardiography for evaluating left atrial function in patients with coronary slow flow phenomenon: a case control study.

BACKGROUND: Coronary slow flow phenomenon (CSFP) involves the delayed opacification of the coronary distal vessel, in the absence of an obstructive lesion in the epicardial coronary artery during angiography. Since the link between left atrial (LA) function and decreased left ventricular function is still unclear, we evaluated LA function using real-time three-dimensional echocardiography (RT3DE) in patients with CSFP, and subsequently determined the incremental value of RT3DE. METHODS: This study enrolled 60 patients with CSFP and 45 control subjects. CSFP was diagnosed based on thrombolysis in myocardial infarction frame count (TFC). The LA phasic volume and function was evaluated by both two-dimensional echocardiography (2DE) and RT3DE. RESULTS: The LA maximal volume (Volmax), pre-systolic volume (Volp), and minimal volume (Volmin) increased, but LA total and active ejection fraction decreased in patients with CSFP. Based on our results, Volmax, Volp, Volmin, and LA total and active ejection fraction correlated with TFC, and with the number of arteries involved. The LA total ejection fraction by RT3DE was the only independent predictor for CSFP (odds ratio, 0.64 [95% confidence interval, 0.49-0.83]; P = 0.001). Also, the LA total ejection fraction by RT3DE demonstrated good predictive power for CSFP, with a cut-off value of 54.15% (area under curve, 0.85; sensitivity, 84%; specificity, 83%). CONCLUSIONS: The LA reservoir and contractile function decreased in the patients with CSFP and correlated with coronary flow rate and with the number of arteries involved. The LA total ejection fraction by RT3DE can independently predict CSFP, and RT3DE demonstrated incremental value for evaluating LA phasic function in the patients with CSFP compared to 2DE.