Wally Ahmar

Outcomes After Primary Percutaneous Coronary Intervention for ST-Elevation Myocardial Infarction Caused by Ectatic Infarct Related Arteries

BACKGROUND There is minimal published data on outcomes of patients presenting with ST elevation myocardial infarction (STEMI) due to an ectatic infarct-related artery (EIRA). The aim of this study was to analyse the clinical characteristics and outcomes of these patients presenting for primary percutaneous coronary intervention (P-PCI) in comparison with non-EIRA. METHODS Of the 1834 patients who presented at our institution for P-PCI between February 2008 and November 2013, 25 (1.4%) were identified as having an EIRA. These patients were compared with those with non-EIRA (80 patients) who were age, gender and lesion matched. Further sub-group analysis on in-hospital and long-term outcomes was done comparing EIRA stented and non-stented patients. Clinical events evaluated include death, recurrent infarction, unstable angina, or target lesion revascularisation (TLR). RESULTS Baseline characteristics were similar between patients with EIRA and non-EIRA although none of those with EIRA had diabetes mellitus. By comparison to the non-EIRA group, the major procedural differences for patients with EIRA were (1) a greater incidence of large thrombus burden (96.0% vs 22.5%, p=0.0001), (2) increased usage of peri-procedural glycoprotein IIb/IIIa inhibitors (72.0% vs 37.5%, p=0.01) and post-procedural anticoagulation (28.0% vs 5.0%, p=0.004), (3) larger mean stent dimension (3.9±0.8mm vs 3.4±0.6mm, p=0.04) and (4) a higher percentage of P-PCI cases that did not have stent deployment (44.0% vs 7.5%, p=0.0001). Patients with STEMI from EIRA had similar in-hospital outcomes but a higher long-term incidence of composite cardiovascular events at mean follow-up of 36.6±14.1months (44.0% vs 16.3% for non-EIRA, p=0.01). Although patients with EIRA who received stenting had better in-hospital outcomes than the non-stented cohort (composite cardiovascular event rate: 0.0% vs 36.4%, p=0.03), long-term outcomes were comparable (35.7% vs 54.6%, p=0.59) due to a relatively high frequency of non-fatal MI and unstable angina in both groups. CONCLUSION Patients with STEMI due to EIRA carry worse long-term outcomes than those with non-EIRA. While successful stent deployment in the setting of EIRA improves procedural and inpatient success rates, it does not necessarily convey benefit to long-term event rates due to recurrent acute coronary syndromes.