Slow coronary flow: a distinct angiographic subgroup in syndrome X.

Patients evaluated for chest pain with angiographically normal coronary arteries are usually labelled syndrome X. A portion of these patients may not have a cardiac cause for their symptoms. The authors aimed to study a subset within this group who showed the phenomenon of slow coronary flow (SCF) as evidenced by a slow antegrade progression of the dye on the coronary arteriogram to see if this could be used as a marker of myocardial ischemia. This observational study included 207 patients being evaluated for suspected coronary artery disease and found to have normal coronary angiograms. SCF was seen in 49 of these patients (23.7%) while the remaining 158 (76.3%) had normal coronary flow (NCF), as detected by the corrected thrombosis in myocardial infarction (TIMI) frame count method (TIMI frame count more than 2 SD of normal). Forty of the 49 patients (82%) in the SCF group had classical angina as compared with only 51 of the 158 patients (32%) in the NCF group (p<0.01). Also, a definitively positive exercise test was observed more commonly in the SCF group than in the NCF group (71% vs 42%, p < 0.01). The authors conclude that SCF patients constitute a definite subset within the wide spectrum of syndrome X and that the phenomenon of SCF could be used as a marker for myocardial ischemia.