JASE: Echo can ID subclinical cardiac dysfunction
“Unfavorable levels of blood pressure, body weight and serum lipids, as well as smoking, diabetes and impaired renal function, increase the risk for cardiovascular morbidity and mortality, but little is known about their influence on cardiac function in the general population,” wrote Havard Dalen, MD, PhD, from the department of circulation and medical imaging and the department of public health at Norwegian University of Science and Technology in Trondheim, Norway, and colleagues.
Scarce data exist on the association between cardiac function and risk factors in low-risk populations. Dalen and co-authors “hypothesized that unfavorable levels of blood pressure, BMI, serum lipids, glucose and renal function were associated with reduced cardiac function, on the basis of echocardiographic measurements.”
The authors used traditional echocardiographic measures as well as tissue Doppler and speckle-tracking to study the association. A total of 1,266 patients from the Nord-Trøndelag Health Study (HUNT) participated in the study, all of whom were believed to be negative for cardiovascular disease, hypertension or diabetes. The study included 663 women and 603 men, with a mean age of approximately 49 years.
The authors found that older age, higher blood pressure, higher BMI and higher non-high-density lipoprotein (HDL) were all associated with lower indices of left ventricular (LV) systolic and diastolic function. This translated to a 5 percent reduction in LV strain per 5 kg/m2 increase in BMI and a 4 percent reduction in LV strain per 10 mm Hg increase in diastolic blood pressure.
In women, having ever smoked was also associated with lower indices of LV systolic and diastolic function but not in men. Meanwhile, in men, lower estimated glomerular filtration rate (eGFR) was associated with reduced indices of LV systolic and diastolic function, which was not observed in women. For both sexes, ever smokers had a 4 to 5 percent reduced systolic and early diastolic right ventricular (RV) function compared with those who had never smoked.
The authors found that reduced LV function was also seen at the low end of the BMI distribution, indicating a J-shaped association among men and women. A similar association was observed between diastolic blood pressure from 50 to 60 mm Hg and reduced LV strain in men. Dalen considered that these “associations may suggest that low diastolic pressure or very low BMI could be signs of preclinical reduced cardiac function, or not yet acknowledged disease, also in apparently healthy individuals.”
“In this population study of 1,266 men and women without known cardiovascular disease, hypertension, or diabetes, conventional cardiovascular risk factors were clearly associated with LV and RV function as assessed by tissue Doppler and speckle-tracking echocardiography. Thus, cardiac function was gradually reduced with increasing blood pressure, BMI, and non-HDL cholesterol and with decreasing HDL cholesterol and eGFR,” Dalen and co-authors wrote.
The authors noted that, except for smoking, the strength of associations between risk factors was consistently stronger for LV than RV function.
“Previously, some echocardiographic studies have suggested that patients with hypertension, metabolic syndrome, diabetes, renal failure, or obesity may have subclinical cardiac dysfunction and that cardiac function decreases with age also in people without cardiovascular disease,” the authors stated. “However, few studies have addressed whether cardiac function in healthy people, assessed by modern echocardiographic methods, is associated with blood pressure, serum lipids, renal function, or BMI.
“The results of this study suggest that conventional risk factors are reliable and consistent markers for cardiac function and not only markers of future morbidity and mortality.”
Follow-up was not available due to the study being a cross-sectional investigation into healthy individuals. The authors also noted that participants were Northern European Caucasians, which could limit the generalizability of the findings to other ethnic groups.
“[W]e found that unfavorable levels of conventional risk factors were clearly associated with reduced LV and RV function, suggesting the possibility of subclinical cardiac dysfunction. The findings suggest that these risk factors influence cardiac function many years before clinical detection,” the authors wrote.
Dalen and colleagues finished by saying that the “J-shaped associations of diastolic blood pressure and body mass with LV function indicate that very low blood pressure and extreme leanness may be indicators of prevalent but subclinical cardiac dysfunction.”