The effect of verapamil and nitroglycerin on the coronary slow flow phenomenon

Abstract

Objective: The aim of this study was to assess the effect of nitroglycerin and verapamil on the coronary flow in patients with the coronary slow flow (CSF) phenomenon (CSFP). Design and methods: Sixty-four patients with CSF and no stenotic lesions during diagnostic coronary angiography were enrolled and divided into the nitroglycerin group (n=35) and verapamil group (n=29), and 29 patients with normal coronary flow were selected as normal. CSFP was defined as it required 4 or more beats for the contrast media to opacify the distal vasculature. Intracoronary injection of 100–400 μg nitroglycerin or verapamil was not given in patients with CSFP until the coronary flow improved. The coronary blood flow was evaluated by Thrombolysis in Myocardial Infarction frame count (TFC) method in this study. Results: There was no difference regarding the clinical characteristics among the three groups. The basic TFCs of the left anterior descending artery (LAD), left circumflex artery (LCX) and right coronary artery (RCA) were 78.28±19.40, 57.24±14.58, and 56.87±12.47 in the verapamil group, and were 70.84±21.66, 55.33±12.52, and 51.05± 15.35 in the nitroglycerin group, respectively, which were significantly higher than those in the normal controls (LAD 29.15±4.42, LCX 23.14± 3.48 and RCA 19.72±1.75, respectively). After the administration of drugs, the TFCs of LAD, LCX and RCA were 42.32±8.88, 36.65±6.78, and 30.32±5.94, respectively (vs. base, all P<0.05) in nitroglycerin group and 37.68±9.31, 31.50±11.30, and 24.58±4.40 respectively (vs. base, all P<0.05) in the verapamil group. The TFCs in both the two groups after the administration of drugs were still higher than that in normal controls (all P<0.05). The TFCs in the verapamil group had a larger decrease than those in the nitroglycerin group (P<0.05). Conclusions: Intracoronary administration of verapamil could result in more improvement of the coronary flow in patients with CSFP than after the administration of nitroglycerin, although the coronary flow was still slower than normal.