BOSTON — Left atrial function is a sensitive predictor of cardiovascular outcome in patients with stable coronary heart disease, a prospective study has shown.
Of 989 patients with heart disease recruited for the ongoing Heart and Soul Study at the San Francisco Veterans' Affairs Medical Center and the University of California at San Francisco, 8.5% of the 247 patients whose left atrial function index was in the lowest quartile had a cardiac event during the 1-year follow-up period, compared with 4% of the 742 whose indices fell into the upper three quartiles, as reported Pamela Y.F. Hsu, M.D., in a poster presentation at the annual meeting of the American Society of Echocardiography.
“The association between a low index and cardiovascular outcomes persisted after adjusting for smoking, congestive heart failure, other comorbid illnesses, medication use, and left ventricular ejection fraction,” said Dr. Hsu of the Mayo Clinic in Scottsdale, Ariz.
To determine the left atrial function index (LAFI), the investigators calculated the time-velocity integral for the left ventricular outflow tract, the left atrial end systolic volume (LAESV) and end diastolic volume (LAEDV), and the LAESV index measurements by using transthoracic echocardiography.
They also measured biplane left atrial volumes and calculated the left atrial ejection fraction (LAESV/LAEDV). The LAFI represents the left ventricular outflow tract time-velocity integral multiplied by the left atrial ejection fraction over the LAESV index, with the whole multiplied by 10 log 4. Using logistic regression, the investigators evaluated the association between the lowest LAFI quartile and cardiovascular outcomes—including myocardial infarction, hospitalization for congestive heart failure, and coronary disease death—and adjusted for potential confounding variables.
In the lowest quartile, the age-adjusted odds ratio for having any cardiac event within 1 year was 3.3, while the specific odds ratios for myocardial infarction, heart failure, and coronary disease death were 3.3, 4.8, and 4.2, respectively.
In the multivariable adjusted model, the odds ratio for any cardiac event was 2.6 and the respective odds ratios for myocardial infarction, heart failure, and coronary disease death were 3.0, 3.3, and 2.2. All of the associations were statistically significant, Dr. Hsu said.
The findings indicate that the LAFI “is a simple, powerful, and clinically useful tool” for predicting 1-year cardiovascular outcomes in coronary heart disease patients, said Dr. Hsu.