The Spontaneous Coronary Slow-Flow Phenomenon: Reversal by Intracoronary Nicardipine.

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 (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 TFC <28 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.