MONTREAL — Diastolic function assessed using speckle-tracking echocardiography is predictive of all-cause mortality in patients with acute coronary syndromes, researchers found.
Using this newer imaging technique, an E/E’ ratio higher than 30 was associated with an increased risk of all-cause death through nearly two years of follow-up (HR 1.82, 95% CI 1.23 to 2.69), according to Sirikarn Napan, MD, of Howard University Hospital in Washington, D.C.
“The E/E’ ratio obtained by this novel method may be a useful addition to existing risk stratification models for risk prediction in patients with acute coronary syndromes,” Napan said at the American Society of Echocardiography meeting here.
Although the E/E’ ratio is a well-validated measure of diastolic function, it is typically assessed with tissue Doppler imaging.
In the current study, the researchers used speckle-tracking echocardiography, which has some advantages, according to Napan. Those include the fact that it is angle independent and can be performed any time offline after the echocardiographic images have been obtained.
Still, there is little data about the prognostic importance of diastolic function in patients with acute coronary syndromes.
So Napan and her colleagues retrospectively studied 246 patients who were admitted to Howard University Hospital for unstable angina, ST-segment elevation MI (STEMI), or non-STEMI and had an echocardiogram performed within 24 hours of admission.
The researchers excluded patients with moderate-to-severe mitral regurgitation or significant mitral annular sclerosis and those who had a history of postoperative acute coronary syndromes, acute MI in the year before admission, and any cardiac procedure in the 90 days before admission.
The speckle-tracking software analyzed the echocardiographic images and provided peak early and late diastolic mitral annular velocities (E’ and A’, respectively) and systolic mitral annular velocities (S’) by averaging values from all four regions.
Pulsed-wave Doppler provided peak early diastolic mitral inflow velocity (E).
The average age of the patients was 62. Most (56.1%) presented with unstable angina, 35.4% had a non-STEMI, and 8.5% had a STEMI.
Overall, 42.7% underwent coronary angiography during admission — 20.3% had a percutaneous coronary intervention and 2% underwent CABG. Follow-up lasted a median of 21 months.
In a multivariate analysis, E/E’ ratio was associated with an increased risk of all-cause death, as was E’/A’ ratio (HR 1.23, 95% CI 1.06 to 1.43). E’ and A’ were negative predictors of death (HRs 0.78 and 0.73, respectively, P<0.05 for both).
The cutoff value of the E/E’ ratio determined to be discriminatory for risk of death was 30, and 23% of patients had a ratio higher than that.
After adjustment for clinical predictors of mortality and conventional echocardiographic parameters, an E/E’ ratio greater than 30 remained predictive of all-cause mortality (HR 1.91, 95% CI 1.09 to 3.32).
Older patients, those with higher creatinine levels, and those with increased posterior wall thickness were significantly more likely to have an E/E’ ratio greater than 30. Males and those with higher left ventricular ejection fractions were less likely to have a ratio that high (P<0.05 for all).
Napan noted some limitations of the study, including the lack of repeated echocardiograms, the lack of information on other outcomes like heart failure and recurrent MI, and lack of a comparison of E/E’ calculated by speckle-tracking echocardiography and by tissue Doppler imaging.
There have been two studies comparing the two techniques, although they yielded conflicting results, she said. One found a good correlation between the two and the other found a poor correlation.
Napan and her colleagues are currently performing a study to compare E/E’ measured with speckle-tracking echocardiography with that obtained by invasive measurement by cardiac catheterization.
In a future study, Napan said she would like to explore the prognostic value of E/E’ in a prospective fashion using both speckle-tracking echocardiography and tissue Doppler imaging to find out which technique is better.
Napan reported that she had no