ACC: Tissue Doppler Imaging Predicts Heart Death Risk

By Todd Neale
CHICAGO, April 3 -- An enhancement of Doppler echocardiography that measures the velocity of myocardial motion seems to be a more accurate predictor of heart-disease mortality in the next five years than the older imaging technique.
Even in the presence of normal echo scans in a community study, tissue Doppler imaging was more sensitive than standard Doppler echo in predicting the risk of death, Rasmus Mogelvang, M.D., of Gentofte University Hospital in Copenhagen, reported at the American College of Cardiology meeting here.
"Despite constantly developing medical therapies and devices to prevent heart failure and improve prognosis," he said, "early identification of high-risk patients with preclinical left ventricular dysfunction is necessary."
However, only half of patients with congestive heart failure show evidence of systolic or diastolic dysfunction using conventional electrocardiography, according to Dr. Mogelvang. So he and colleagues set out to compare the prognostic value of tissue Doppler imaging.
They randomly selected 1,036 men and women from the fourth Copenhagen City Heart Study and evaluated them using both imaging techniques.
Through the end of a mean follow-up of 5.1 years 90 participants had died. At baseline, those who later died were significantly older (P<0.001) and more likely to have hypertension (P<0.001), diabetes (P<0.04), ischemic heart disease (P<0.001), a left ventricular ejection fraction of less than 50% (P<0.05), and left ventricular hypertrophy (P<0.001) than those who lived to the end of the study.
On tissue Doppler imaging readings from six mitral annular sites, the researchers identified one positive peak of systolic velocity and two negative peaks of diastolic velocity: early and late.
Those who did not die before the end of follow-up had higher values of systolic velocity (6.1 versus 5.3 cm/second), late diastolic (6.7 versus 6.3 cm/second), and early diastolic (7.2 versus 5.4 cm/second) than those who later died.
For both systolic velocity and late diastolic, participants in the lowest tertile of myocardial velocities had a relative risk of 1.25 for dying with each 1-cm/second increase compared with the highest tertile (P<0.04 and P<0.001 for systolic velocity and late diastolic, respectively) after adjusting for variables including age, sex, heart rate, body mass index, hypertension, diabetes, and ischemic heart disease.
Multivariable analysis revealed that late diastolic did not have the same predictive value (P=0.77).
It has been suggested, Dr. Mogelvang said, that the mitral annular velocities are inter-related, leading the researchers to create a new prognostic index that combines information on systolic and diastolic function from tissue Doppler imaging: (early diastolic/late diastolic)/systolic velocity.
In a multivariate analysis, participants in the lowest tertile of values on this index had a relative risk of 2.6 (95% CI 1.4 to 4.7, P<0.003) for dying compared with those in the highest tertile.
This relationship was independent of conventional echocardiographic readings.
"That means that even when conventional echocardiography indicates normal cardiac function," said Dr. Mogelvang, "the combined information of systolic and diastolic function from tissue Doppler imaging provides prognostic information."
He added that this technique is not ready for clinical use because there are no established values for normal or abnormal peak mitral annular velocities.
"Before we can use it in daily practice, we need to set the cut-off values, and I hope this study will pave the way for such studies," he said.
One of Dr. Mogelvang's co-authors has received consulting fees from GE Healthcare.
Primary source: American College of CardiologySource reference:Mogelvang R, et al "Echocardiographic tissue Doppler imaging is a powerful independent prognosticator of overall mortality in the general population: results from the fourth Copenhagen City Heart Study (2002-2007)" ACC Meeting 2008; Abstract 409-2.