Abstract 18996: Impact of Infarct Size on Left Ventricular Diastolic Function Following Acute Myocardial Infarction

Introduction: Severe left ventricular diastolic dysfunction is associated with worse prognosis after acute myocardial infarction (MI). Twenty percent of patients have a restrictive filling pattern (RFP) following MI, and this is associated with a fourfold increase in mortality. The determinants of diastolic function in this setting are not well defined. Aim: We sought to determine the correlation between enzymatic infarct size and RFP in patients with a first ever MI. We hypothesized that a larger infarct size would result in greater impairment of left ventricular diastolic function. Methods: Data analysis was performed on consecutive patients admitted with first ever non-ST elevation MI (NSTEMI) or ST-elevation MI (STEMI) to a single large tertiary referral hospital from January 2013 to December 2014. All patients underwent coronary angiography during the index admission. Infarct size was determined by peak troponin I. Doppler transmitral flow pattern was obtained from the initial transthoracic echocardiogram performed within 48 hours of admission. RFP was defined as: E/A ratio >2.0 and/or E-wave deceleration time <160ms (American Society of Echocardiography Guidelines 2009). Results: Data were available on 645 consecutive patients who underwent coronary angiography for MI. We excluded 160 patients with a previous MI. Of the remaining 485 patients (mean age 62±13 years; mean left ventricular ejection fraction (LVEF) 53±12%), there were 338 NSTEMIs (70%) and 147 STEMIs (30%). PCI was performed in 360 (74%) patients (single vessel (82%), ≥2 vessels (18%)); coronary artery bypass surgery in 58 (13%); and medical management in 67 (13%). Sixty-nine patients (14.4%) had RFP; 52% of these had a LVEF ≥45%. Peak troponin I levels were higher in the RFP group (31.8±30.9μg/L vs 16.8±25.2μg/L, p=<0.001). On multivariate analysis, infarct size by peak troponin I (OR 1.02, 95%CI 1.00-1.03, p=0.026) and low LVEF (OR 0.95, 95%CI 0.91-0.99, p=0.015) were the only independent predictors of RFP. Conclusion: Infarct size was a major determinant of diastolic dysfunction following first ever MI. Whilst LV systolic dysfunction was strongly associated with impaired diastolic function, 52% of patients with severe diastolic dysfunction had relatively preserved LVEF.