Aims: We hypothesised that ischaemic preconditioning (IP) results from complex cellular mechanisms without significant collateral recruitment or clinical pre-intervention interference.
Methods and results: A total of 58 patients underwent three 2-min balloon inflations separated by 5-min reperfusions. Anginal symptoms were graded according to this scale: 0 = absent, 1 = mild, 2 = moderate and 3 = severe. ST-segment shift and QT dispersion (QTd) were measured from 12 lead ECGs. Ejection fraction (EF) was assessed by 2D echo and collateral flow recruitment by collateral flow index (CFI). Anginal scores were 2.4+/-0.6, 1.7+/-0.5 and 1.2+/-0.6 (p<0.05); ST-segment shifts were 6.0+/-2.1, 3.8+/-1.8, and 1.9+/-1.2 mm (p<0.05); QTd increased from a baseline value of 39+/-24 to 96+/-27 (p<0.05) and decreased to 66+/-23 and 45+/-16 ms, at the end of the first, second and third inflation, respectively. EF decreased from a baseline value of 63+/-3% to 33+/-2%, 34+/-3%, and 36+/-5% in the three inflations. The CFI was approximately 0.15 in all ischaemic periods.
Conclusion: These results suggest that IP does occur during repeated brief coronary artery occlusion in patients with a low likelihood of both collateral recruitment and clinical pre-intervention interference.