Left Atrial Function by Cardiac CT Is a Strong Predictor of Heart Failure and Cardiac Death

Introduction: Despite recent improvements in heart disease outcomes, congestive heart failure (CHF) remains a common disease with a dire prognosis. The ability to identify patients at risk for CHF, at an early stage, would enable appropriate treatment to be applied earlier, which may improve outcome. Currently echocardiography remains the main technique for identifying patients at risk, but it has limitations especially in predicting raised filling pressures. We wished to investigate the ability of left atrial (LA) function by CT to identify a combined outcome of CHF hospitalization and cardiac mortality.

Methods: 460 consecutive patients who had undergone cardiac CT using continuous spiral scanning were retrospectively identified. Automatic calculation of maximum and minimum LA and left ventricular (LV) chamber volumes was performed. LA emptying fraction (LATEF) was calculated as the percent total change in LA volume. 187 patients had undergone echocardiography within 6 months of CT (Echo-group). Patients were followed up for a mean of 6 years.

Results: The mean age was 60±14, 63% were men, 27% had a previous myocardial infarction (MI), 65% had a history of hypertension and 39% were diabetic. Mean EF was 59±16% and mean LATEF was 40±11%. An optimal threshold for LATEF of 37.5% was found to best identify raised filling pressures (grades 2 and 3 diastolic dysfunction) in the Echo-group, using ROC analysis. This threshold identified 39 of 49 events. See Kaplan-Meier curve below. Using Cox regression analysis, correcting for age, previous MI, LA volume and end-systolic LV volume, LATEF remained a significant predictor of the combined end-point (CHF hospitalisation and cardiac death, HR 0.94, p<0.001), as well as each component separately.

Conclusion: In this large consecutive group of patients undergoing cardiac CT (spiral technique), left atrial function, expressed as LATEF was a powerful predictor of CHF and cardiac death.