Objective: To assess the efficacy of intracoronary nitroglycerin and verapamil for patients with the coronary slow flow phenomenon (CSFP).
Methods: Sixty-four patients with CSFP without stenotic lesions during diagnostic coronary angiography were enrolled and divided into the nitroglycerin group (n = 35) and verapamil group (n = 29), 29 patients with normal coronary flow served as normal control. CSFP was defined when 4 or more heart beats were needed for contrast media to opacify the distal vasculature. Intracoronary injection of 100 - 400 microg nitroglycerin or verapamil through the diagnostic catheter was applied to patients with CSFP to improve coronary flow. The coronary blood flow was evaluated by thrombolysis in myocardial infarction (TIMI) frame count (TFC) method.
Results: Clinical characteristics were similar among the three groups. The basic TFCs of left anterior descending artery (LAD), left circumflex artery (LCX) and right coronary artery (RCA) were 78.3 +/- 19.4, 57.2 +/- 14.6, 56.9 +/- 12.5 in the verapamil group, and were 70.8 +/- 21.7, 55.3 +/- 12.5, 51.1 +/- 15.4 in the nitroglycerin group, respectively, which were significantly higher than those in the normal controls (LAD 29.2 +/- 4.4, LCX 23.1 +/- 3.5 and RCA 19.7 +/- 1.8, respectively). After the administration of drugs, the TFCs of LAD, LCX and RCA were 42.3 +/- 8.9, 36.7 +/- 6.8, 30.3 +/- 5.9 respectively (all P < 0.01 vs. baseline) in the nitroglycerin group and 37.7 +/- 9.3, 31.5 +/- 11.3, 24.6 +/- 4.4 respectively (all P < 0.01 vs. baseline) in the verapamil group. The TFCs after drug administration in both therapy groups were significantly higher than that in normal controls (all P < 0.05). The TFCs decrease in the verapamil group were more significant than that in the nitroglycerin group (all P < 0.05).
Conclusion: Intracoronary administration of verapamil could result in more coronary flow improvement in patients with CSFP than nitroglycerin, although the post therapy coronary flow was still slower than normal.