What is the clinical evidence from this study?

Study design: Cohort. Population: ST elevation myocardial infarction (STEMI) (n=199). Intervention: Left atrial (LA) fractional change assessment by CMR vs. LA maximal volume (LAmax). Primary outcome: Major adverse cardiac event (MACE) including death, re-infarction, stroke, and admission for heart failure (adjusted HR 0.66, 95% CI 0.46-0.95).

June 12, 2012Open Access

Left atrial volume and function in patients following ST elevation myocardial infarction and the association with clinical outcome: a cardiovascular magnetic resonance study

Key Result

In STEMI patients, left atrial fractional change assessed by CMR was independently associated with MACE (adjusted HR 0.66; 95% CI 0.46-0.95) and provided incremental prognostic value over LAmax.

Study Design

Type

Cohort (n=199)

Structured PICO

Does LA fractional change measured by CMR predict MACE in patients following STEMI?

Population

199 patients following ST elevation myocardial infarction (STEMI)

Intervention

Cardiovascular magnetic resonance (CMR) scan performed within 1-3 days after STEMI to measure left atrial (LA) function, specifically LA fractional change

Outcome

Major adverse cardiac event (MACE), defined as the composite of death, re-infarction, stroke, and admission for heart failurecomposite

Impaired LA fractional change measured by CMR provides incremental prognostic information for MACE beyond established predictors including LA maximal volume in STEMI patients.

Main Result

Effect estimate: adjusted HR 0.66 (95% CI 0.46-0.95)

Abstract

AIMS: The left atrium (LA) transfers blood to the left ventricle in a complex manner. LA function is characterized by passive emptying (LA passive fraction), active emptying (LA ejection fraction), and total emptying (LA fractional change). Despite this complexity, the clinical relevance of the LA is based almost exclusively on LA maximal volume (LAmax), which may not glean the full prognostic potential. Cardiovascular magnetic resonance (CMR) is considered the most accurate method for studying LA function and size. The aim of the present study was to evaluate the prognostic importance of LA function in patients following ST elevation myocardial infarction (STEMI). METHODS AND RESULTS: In 199 patients, a CMR scan was performed within 1-3 days after STEMI to measure LAmax and minimal volume (LAmin) and LA function. The incidence of death, re-infarction, stroke, and admission for heart failure major adverse cardiac event (MACE) were registered during the follow-up period 2.3 years (inter-quartile range: 2.0-2.5). A total of 40 patients (20%) met the clinical endpoint of MACE during follow-up. In a Cox regression analysis adjusting for known risk factors, LA fractional change remained independently associated with MACE adjusted hazard ratio: 0.66 (95% confidence interval: 0.46-0.95). LAmax, LAmin, or LA passive fraction was not independently associated with MACE. Furthermore, LA fractional change provided incremental prognostic value to LAmax and other known predictors (Wald χ(2) 31.0 vs. 39.9, P= 0.016). CONCLUSION: In STEMI patients, impaired LA fractional change is independently associated with outcome and provide incremental prognostic information to established predictors including LAmax.