Left atrial enlargement and phasic function in patients following non-ST elevation myocardial infarction.

Background: Changes in left atrial (LA) volumes after ST elevation myocardial infarction are reported but have not been well described following non-ST elevation myocardial infarction (NSTEMI).

Methods: Seventy-five patients with NSTEMIs were studied within 48 hours of presentation and in follow-up at 6 and 12 months; they were compared with age-matched normal controls (n = 100). Biplane indexed LA volumes were measured, and phasic LA volumes (conduit, passive, and active emptying) were calculated. LA remodeling was defined as an increase in LA maximum volume over 12 months.

Results: LA maximum volume was significantly larger at baseline in patients with NSTEMIs. At 12 months, maximum LA volume increased (27.6 ± 7.4 vs 30.2 ± 8.9 mL/m² P = .002), with LA remodeling present in 64% of the patients with NSTEMIs. LA passive emptying volume increased, with concurrent reductions in conduit and active emptying volumes. Although diabetes, major coronary artery disease, and a larger myocardial score were predictive of LA remodeling, E' velocity was the only independent predictor.

Conclusions: Patients with NSTEMIs had progressive LA enlargement with reductions in conduit and active emptying volumes, reflecting persistent left ventricular diastolic dysfunction consequent to coronary artery disease and associated diabetes. The measurement of LA volumes after NSTEMI may be useful to monitor chronic diastolic dysfunction resulting from ischemic burden.