BACKGROUND: We have recently demonstrated that a single oral administration of sarpogrelate, a 5-HT(2A) receptor antagonist, may improve exercise capacity in anginal patients with well-developed collaterals. The aim of the current study was to investigate the effectiveness of 2-week treatment with sarpogrelate on anginal symptoms and exercise capacity in anginal patients. METHODS: A treadmill exercise test was repeated after a 2-week period with or without sarpogrelate (100 mg 3 times a day) in 20 patients with angiographically proven stable angina. Anginal symptoms and daily physical activity by the specific activity scale (SAS) were also evaluated. RESULTS: Treatment with sarpogrelate significantly increased the SAS score and prolonged exercise time to the onset of 0.1-mV ST depression. When data were analyzed in a subgroup of patients (n = 8) with well-developed collaterals, the treatment with sarpogrelate decreased the number of anginal attacks (control vs sarpogrelate, 3.0 +/- 2.8 vs 0.9 +/- 1.1/2 weeks, P <.05), increased the SAS score (5.2 +/- 1.6 vs 6.2 +/- 1.3 METS, P <.05), and increased the time to the onset of 0.1-mV ST depression (235 +/- 84 vs 295 +/- 127 seconds, P <.05). In addition, the double product at the onset of 0.1-mV ST depression increased by 15% (P <.05) after sarpogrelate. In contrast, all parameters were not significantly changed after sarpogrelate treatment in patients (n = 12) without well-developed collaterals. CONCLUSIONS: These findings indicate the therapeutic effectiveness of sarpogrelate for anginal patients, especially for patients with well-developed collaterals.