Effect of time interval between two balloon inflations on ischemic preconditioning during coronary angioplasty

Ischemic preconditioning, defined as a reduction in myocardial ischemia caused by repeated brief episodes of coronary occlusions, is observed during percutaneous transluminal balloon angioplasty (PTCA). To elucidate the effects of the length of the interval between consecutive balloon inflations on ischemic preconditioning during PTCA, we examined 62 patients with chronic stable angina (48 males and 14 females; mean age 62 +/- 10 yr). PTCA was performed on the left anterior descending artery lacking in collateral vessels. A 2-min balloon inflation was performed twice and the extent of ST segment elevation in the electrocardiogram and the severity of chest pain (scored from 0 to 10) for each inflation were determined and compared. Patients were divided into three groups according to the interval between the two inflations: 1 min, Group 1; 2 min, Group 2; and 5 min, Group 5. In Groups 2 and 5, ST-segment elevation was significantly decreased during the second balloon inflation, as compared with that during the first inflation (P < 0.01, P < 0.001). A significant decrease was also observed in the severity of chest pain (P < 0.05, P < 0.01). However, Group 1 showed no significant decrease in ST-segment elevation or severity of chest pain between the first and second inflations. ST-segment elevation and chest pain were reduced to a greater extent in Group 5 than in Group 2. Results suggest that an interval of more than 2 min between balloon inflations is required to achieve ischemic preconditioning during PTCA.