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Population Study of Tissue Doppler Echocardiography

Rasmus Møgelvang

Summary

Background: Heart failure is a condition with high morbidity and mortality. With increasing incidence, it constitutes a major public-health problem. In order to prevent heart failure and improve prognosis, early identification of subjects at high risk is necessary. Tissue Doppler imaging might have the potential of detecting preclinical cardiac dysfunction, however, it prognostic and diagnostic abilities in the general population have not been investigated.

Objectives: To examine the diagnostic and prognostic value of tissue Doppler imaging compared with conventional echocardiography in the general population.

Hypotheses: Systolic and diastolic myocardial dysfunction assessed by tissue Doppler imaging is associated with 1) risk factors for heart failure, such as hypertension, diabetes, and ischemic heart disease; 2) elevated plasma proBNP concentration according to age and sex; and 3) mortality.

Methods: Within the 4th examination of the Copenhagen City Heart Study, a large populationbased cardiovascular study, cardiac function was evaluated in 1,100 randomly selected participants both by tissue Doppler imaging and conventional echocardiography. Clinical data included information about age, sex, heart rate, body mass index, hypertension, diabetes, ischemic heart disease, and estimated glomerular filtration rate. Participants were followed from the examination in 2002 through to 2003 until August 2007 or time of death.

Results: Tissue Doppler imaging revealed impaired systolic and diastolic cardiac function, independently of clinical and conventional echocardiographic information, in hypertension, diabetes, and ischemic heart disease compared to controls. A significant age-dependency was observed for all the tissue Doppler imaging parameters. Reduced systolic and diastolic performance by tissue Doppler imaging in terms of a reduced peak systolic (s’) or peak late diastolic (a’) longitudinal mitral annular velocity or high eas-index (e’/(a’× s’)) were significant and independent predictors of elevated plasma proBNP concentrations and mortality. Furthermore, the eas-index correlated linearly with plasma proBNP concentrations even in the in the subgroup of persons with a plasma proBNP within the normal range and absence of left ventricular hypertrophy, dilatation, ejection fraction <50%, and severe diastolic dysfunction by conventional echocardiography. Stratifying the population into tertiles of the eas-index, showed that the risk of mortality increased with increasing eas-tertiles; thus persons with a high eas-index had a risk of death 2.5 times as great as persons with a low eas-index despite adjustment for clinical and conventional echocardiographic information. Conversely, conventional echocardiography provided no additional information of death.

Conclusions: In the general population, tissue Doppler imaging reveals impaired cardiac function in persons with hypertension, diabetes, or ischemic heart disease. Impaired cardiac function by tissue Doppler imaging is associated with increased plasma proBNP and mortality. Furthermore, increased plasma proBNP and increased mortality correlate with impaired cardiac function by tissue Doppler imaging, even when conventional echocardiography gives the impression of normal cardiac function.