Longitudinal left ventricular function is globally depressed within a week of STEMI

Abstract

Sixty percent of stroke volume (SV) is generated by atrioventricular plane displacement (AVPD) in a healthy left ventricle (LV). The aims were to determine the effect of ST-elevation myocardial infarction (STEMI) on AVPD and contribution of AVPD to SV and to study the relationship between AVPD and infarct size (IS) and location. Patients from CHILL-MI and MITOCARE studies with cardiovascular magnetic resonance within a week of STEMI (n = 177, 59 ± 11 years) and healthy controls (n = 20, 62 ± 11 years) were included. Left ventricular volumes were quantified in short-axis images. AVPD was measured in six locations in long-axis images. Longitudinal contribution to SV was calculated as AVPD multiplied by the short-axis epicardial area. Patients (IS 17 ± 10% of LV) had decreased ejection fraction (48 ± 8%) compared to controls (60 ± 5%, P<0·001). Global AVPD was decreased in patients (11 ± 2 mm versus 15 ± 2 mm in controls, P<0·001) and this held true for both infarcted and remote segments. AVPD contribution to SV was lower in patients (58 ± 9%) than in controls (64 ± 8%) (P<0·001). There was a weak negative correlation between IS and AVPD (r2=0·06) but no differences in global AVPD linked to infarct location. Decrease in global and regional AVPD occur even in remote myocardium within 1 week of STEMI. Global AVPD decrease is independent of MI location, and MI size has only minor effect. Longitudinal pumping is slightly lower compared to controls but remains to be the main component to SV even after STEMI. These results highlight the difficulty in determining infarct location and size from longitudinal measures of LV function.