Coronary slow flow: Benign or ominous?

Objective: Coronary slow flow phenomenon has been arbitrarily defined as delayed coronary blood flow in the absence of obstructive coronary artery disease. The present study sought to investigate the clinical features, natural history, and outcomes of affected patients.

Methods: In this prospective cross-sectional study, 217 consecutive patients who had undergone coronary angiography and showed features of coronary slow flow phenomenon were evaluated for demographic and coronary risk factor profile, as well as clinical outcomes, at baseline and following treatment.

Results: The study population consisted of 165 (76%) males and 52 (24%) females. The mean age of patients was 52.6±10 years. Mean ejection fraction was 48.2±5.4, 39.3% had diabetes, 43.3% had hypertension, 49.8% was a cigarette smoker, 41.9% had dyslipidemia, and 15% had a familial history of cardiac disease. Forty-nine percent was detected to have abnormal hsCRP levels. The most prevalent presenting complaint was atypical chest pain. Fifty-four percent of patients had slow blood flow in all three vessels. Thirty-six people had undergone repeat coronary angiography in a follow-up period of 5-7 years due to persisting or worsening clinical symptoms, of whom 6 (16.6%) showed significant coronary artery stenosis. Eight (22.2%) had mild CAD, and the rest still showed coronary slow flow without significant stenosis. The most common complaint during follow-up and after initiation of medical therapy was nonanginal chest pain.

Conclusion: Patients with coronary slow flow phenomenon are predisposed to atherosclerosis and obstructive coronary artery disease. Therefore, this pathology should not be considered as a totally benign condition. Primary and secondary cardiovasculature preventive measures should be constituted and seem worthwhile in this patient population.