No-flow has been reported after 10-15% of percutaneous interventions on degenerated saphenous vein grafts. In this prospective study of 36 degenerated saphenous vein graft lesions (32 patients), no-flow (TIMI flow < 3 in the absence of a significant lesion or dissection) occurred in 15/36 (42%) lesions. A total of 32 episodes of no-flow occurred after angioscopy (n = 14), extraction atherectomy (n = 10), balloon angioplasty (n = 2) or stent implantation (n = 6). Intragraft nitroglycerin (100-300 micrograms) alone resulted in no improvement in TIMI flow in the setting of no-reflow (TIMI flow 1.2 +/- 0.6 to 1.4 +/- 0.8, P = NS). Intragraft verapamil (100-500 micrograms) resulted in improvement in flow in all 32 episodes (TIMI flow 1.4 +/- 0.8 before, to 2.8 +/- 0.5 after verapamil, P < 0.001). Although verapamil increased TIMI flow after all episodes of no-reflow, two (6.3%) had persistent no-reflow (TIMI 1) despite verapamil, associated with non-Q wave myocardial infarction. In conclusion, treatment of no-reflow with verapamil during degenerated vein graft interventions was associated with reestablishment of TIMI 3 flow in 88% of cases. In contrast, intragraft nitroglycerin alone was ineffective for reversing no-reflow.