Abstract 11499: Preinfarction Angina Alters the Relationship Between Infarct Size and Duration of Ischemia
Preinfarction angina (PIA) may be a clinical surrogate of ischemic preconditioning where transient episodes of chest pain prior to ST-elevation myocardial infarction (STEMI) may result in significant myocardial protection. Although multiple studies have demonstrated the protective effect of Preinfarction angina, they were mostly performed in the pre-stent era and did not correct for important confounding factors like duration of ischemia and myocardial area- at-risk. We therefore investigated if PIA shows similar benefits in patients treated with primary PCI in the setting of STEMI. We performed a retrospective analysis of 247 consecutive patients admitted to our institution with STEMI who met the inclusion criteria of TIMI 0 flow on presentation and ischemic time between 1 and 6 hours. We confirmed that peak CK was an accurate measurement of infarct size in a subgroup of patients that underwent cardiac MRI. Infarct size by peak CK and troponin was lower in patients with PIA compared to patients without (1094+/-75 vs. 2270+/-102 and 4.2 +/-0.4 vs. 6.7+/-0.4, p<0.0001). Ejection fraction measured by echocardiography 48 hours later was almost 4% higher in patients with PIA (51.4+/-1.2% vs. 47.6+/-1.0%, p<0.02). Total CK remained highly statistically different between PIA and non-PIA patients when corrected for ischemic times (181 vs 185 mins) and area-at-risk. A highly correlated linear increase in peak CK vs ischemic time was observed in non-PIA patients (Fig.1). However, in PIA patients, no such correlation could be seen, confirming the protective effect of PIA in patients with STEMI and up to 6 hours of ischemia. This is the largest study to date of assessing the effects of PIA in patients treated with primary PCI and stenting. Furthermore, it is the first study to account for the myocardial area-at-risk and stratify by the duration of ischemia. The presence of PIA continues to be a powerful protector against myocardial infarction in the stent era.
- © 2011 by American Heart Association, Inc.