An under-recognized cause of chest pain, the coronary slow-flow (CSF) phenomenon is characterized by delayed coronary opacification during diagnostic angiography in the absence of epicardial coronary artery disease (CAD). Given its angiographic resemblance to no-reflow during percutaneous coronary intervention, a condition associated with microvascular spasm responsive to calcium-channel blockers, we hypothesized that spontaneous CSF may similarly be reversed by intracoronary (IC) nicardipine.The effect of IC nicardipine was evaluated in 30 patients. CSF was defined as spontaneously delayed flow (TIMI 3) during diagnostic coronary angiography in the absence of obstructive epicardial CAD or other conditions associated with impaired flow. Nicardipine was administered as a 200 μg IC bolus, after which repeat angiography was performed. Coronary flow before and after nicardipine was evaluated by TIMI flow grade and corrected TIMI frame count (TFC) assessments.The study population consisted of 22 men and 8 women (mean age, 54 ± 11 years). Clinical presentation was rest angina in 21 patients (70%). At baseline, CSF withTIMI 3 flow was observed in 49 vessels. TFC was prolonged (27) in 68/90 vessels (76%). IC nicardipine produced markedly accelerated coronary filling, which was corroborated by TFC analysis. TFC was 47 ± 17 before vs 15 ± 5 after nicardipine (P.001). All vessels demonstrated TIMI 3 flow and TFC28 after nicardipine treatment.IC nicardipine appears highly effective in reversing spontaneous CSF. These findings implicate microvascular spasm in the pathogenesis of CSF. Future studies of oral calcium-channel blockers in the long-term management of CSF are needed.
