Abstract P122: Postconditioning to Reduce Infarct Size Following Acute Myocardial Infarction
BACKGROUND: Postconditioning (PC) is a novel strategy to reduce reperfusion injury following myocardial infarction through graded restoration of blood flow. Cardiac magnetic resonance (CMR) imaging provides unique tissue characterisation.
METHODS: Patients undergoing primary percutaneous intervention (PPCI) were enrolled into a prospective randomised study to evaluate the feasibility of early CMR imaging to examine the effect of PC. The PC protocol involved 4x1 min serial balloon inflations to re-occlude the artery after restoration of flow. Control patients were stented after 8 mins of unhindered reperfusion. CMR was performed <36 hrs to determine extent of infarction by late gadolinium enhancement (LGE) (figure 1B⇓). Microvascular obstruction (MVO) was represented by areas of low signal on early gadolinium enhanced images (Figure 1A⇓). Results are presented as mean±standard error.
RESULTS: 33 patients were randomised; 19 patients completed the protocol and 14 underwent a successful CMR scan <36 hrs (8 PC, 6 control). Baseline characteristics were similar as was the pain-to-balloon time (mins) (137±24 vs. 183±45; NS). ST-segment resolution (mm), a marker of reperfusion, was improved in the PC group (3.3±0.3 vs. 1.3±0.3; P<0.004). Peak CK release (IU) was not different between the groups (2319±540 con vs. 2010±336 PC; NS) nor was the AUC of CK release over 36 hrs. There was no difference in the area of LGE(g) (25.4±4.9 con vs. 36.8±7.1 PC; NS) at 28±12.9 hours nor MVO(g) (4.18±1.9 con vs. 6.6±3.6 PC; NS). There were no MACE.
CONCLUSIONS: A CMR scan early after PPCI is feasible and provides high quality data. Initial data suggest improved perfusion by PC but no infarct reduction.