Coronary slow-flow causing transient myocardial hypoperfusion in patients with cardiac syndrome X: Long-term clinical and functional prognosis

Background: We investigated the possibility that transient coronary slow-flow as assessed during coronary angiography in patients with cardiac syndrome X may impair myocardial perfusion and the effects of this phenomenon on long-term prognosis. Methods: From 50 consecutive patients with cardiac syndrome X, we prospectively recruited 16 who exhibited coronary slow-flow during angiography. The remaining 34 patients served as controls. The slow-flow phenomenon was invariably worsened by nitrates and reversed by papaverine. During slow-flow, a dose of 99m-Tc-Methoxy-isobutyl-isonitrile (MIBI) was injected in 12 patients and SPECT imaging performed 1 h later. The perfusion study was repeated after 2 days at rest and, in 9 patients, at peak exercise after 10 ± 4 days. Patients were then regularly followed-up. Results: All 12 patients had a significant MIBI defect in the regions served by the coronary artery that showed slow-flow just prior MIBI injection. After exercise, MIBI tomograms revealed a perfusion defect in 5 out of the 9 patients who underwent stress scanning. At 14 ± 2 years follow-up, 1 patient with slow-flow had died and 4 developed significant coronary artery disease (CAD), while all patients of the control group were alive and none had developed significant CAD. Conclusions: These results show that the slow-flow phenomenon might be the cause of transient myocardial underperfusion in patients with angina and normal coronary arteries. Apparently, this phenomenon is associated with a worse cardiac prognosis. Therefore, patients with coronary slow-flow should be carefully followed-up.