Effects of the number and interval of balloon inflations during primary PCI on the extent of myocardial injury in patients with STEMI: does postconditioning exist in real-world practice?

Unlabelled: Postconditioning reduces infarct size in animal models and clinical studies. The present retrospective study aimed to evaluate the effects of the number and interval delay of balloon inflations during primary percutaneous coronary intervention (PCI) on enzymatic infarct size, myocardial perfusion and cardiac function in patients with ST-segment elevation myocardial infarction (STEMI) in routine clinical practice.

Methods: Of the 433 STEMI patients who underwent primary PCI at Vanderbilt University Medical Center from October 2003 to August 2007, 85 (19.6%) met criteria and were enrolled into two groups: those with > or = 3 versus with < or = 2 balloon inflations. Peak CK, ST-segment resolution, myocardial blush grade (MBG) and left ventricular (LV) function were compared between the two groups. Correlations of peak CK, MBG and LV ejection fraction (LVEF) with the number, average duration and the first delay interval of balloon inflations were analyzed. A stepwise multiple regression analysis was used to identify the possible determinants of echocardiographic LVEF.

Results: The LV end-systolic volume (LVESV) index in the group with > or = 3 inflations was significantly lower than that with < or = 2 inflations (33.1 +/- 7.9 ml/m square vs. 37.5 +/- 11.2 ml/m square p = 0.036), while LVEF was significantly higher (50.4 +/- 6.3% versus 46.1 +/- 8.5%; p = 0.009). Post hoc analysis showed peak CK in patients with 4 inflations was significantly lower than that with < or = 2 inflations (1,698 +/- 1,266 IU/L vs. 2,603 +/- 1,532 IU/L; p < 0.05). There was a positive correlation between LVEF and the number of balloon inflations (r = 0.222, p = 0.041).

Conclusions: Repetitive balloon inflations during primary PCI appear to confer cardioprotection. The data suggest that postconditioning may exist in real-world practice and contribute to myocardial protection.