Three minute, but not one minute, ischemia and nicorandil have a preconditioning effect in patients with coronary artery disease

OBJECTIVES This study focused on 1) the determination of the optimal precon ditioning (PC) duration, and 2) the protective effect of nicorandil (NC), a hybrid nitrate with a KATP channel opening effect, during a percutaneous t ransluminal coronary angioplasty (PTCA) model in humans. BACKGROUND The ischemic PC effect is induced in 180 s ischemia, but not in 120 s ischemia in rabbit hearts. However, the duration of ischemia that ind uces PC effect and the role of the KATP channel in the PC effect in humans are still unclear. METHODS Forty-six patients with stable angina were randomly allocated to fo ur groups: the duration of the first inflation as PC ischemia was 60 s in t he PC60 group (n = 12), and 180 s in the PC180 group (n = 12). In the other groups, NC (80 mu g/kg) was intravenously given for 1 min in the NC group (n = 12), and isosorbide dinitrate (ISDN) (40 mu g/kg) was given in the ISD N group (n = 10). Five minutes after first inflation or drug administration , a second inflation was conducted for 120 s in each group. In the EGG, the lead with the largest shift in ST segment (deltaST max), and the sum of el evated ST levels in all leads (sigmaST) were determined. RESULTS In the PC60 group, no significant difference was observed in either deltaST max or sigmaST between the first and second inflation. However; th e second inflation in the PC180 group showed significantly lower levels of deltaST max and sigmaST compared with those of the first inflation. In the NC group, both deltaST max and sigmaST measured at 30 s and 60 s after ball oon inflation were significantly lower than those of the first inflation in the PC60 and PC180 control groups. In the ISDN group, no significant diffe rence was observed in deltaST max or sigmaST. CONCLUSION In human PTCA models, a PC effect is observed in 180 s ischemia, but not in 60 s ischemia. A pharmacological PC effect is induced by NC, a KATP channel opener with a nitrate-like effect but not ISDN. This suggests that the Opening of KATP channels plays an important role in the protecting effect of NC. (J Am Coll Cardiol 2000;35:345-51) (C) 2000 by the American College of Cardiology.