Coronary Slow Flow Phenomenon Clinical Findings and Predictors

In some patients with chest pain, selective coronary angiography reveals slow contrast agent passage through the epicardial coronary arteries in the absence of stenosis. This phenomenon has been designated the slow coronary flow (SCF) phenomenon.

In this study, we aimed to describe the demographic and clinical findings and presence of common atherosclerosis risk factors in patients with the SCF phenomenon.

Between October 2014 and March 2015, demographic data, clinical histories, atherosclerosis risk factors, and laboratory and angiographic findings were recorded for all consecutive patients scheduled for coronary angiography and diagnosed with the SCF phenomenon, as well as a control group (patients with normal epicardial coronary arteries; NECA). SCF was diagnosed based on the thrombolysis in myocardial infarction frame count (TFC). A TFC > 27 indicated a diagnosis of SCF phenomenon.

Among the 3600 patients scheduled for selective coronary angiography, 75 (2%) met the SCF criteria. SCF and NECA patients did not exhibit statistically significant differences in traditional risk factors except for hypertension, which was more prevalent in SCF than NECA patients (52% versus 31%, P = 0.008). A multivariable analysis indicated a low body mass index, presence of hypertension, low high-density lipoprotein cholesterol (HDL-c) level, and high hemoglobin level as independent predictors of the SCF phenomenon; of these, hypertension was the strongest predictor (odds ratio = 6.3, 95% confidence interval: 2.2 - 17.9, P = 0.001).

The SCF phenomenon is relatively frequent, particularly among patients with acute coronary syndrome who are scheduled for coronary angiography. Hypertension, a low HDL-c level, and high hemoglobin level can be considered independent predictors of this phenomenon.