MESA: Multiple CHD risk factors associated with preclinically impaired myocardial perfusion

February 07, 2006

Bethesda, MD - Several traditional cardiovascular risk factors were independently associated with impaired myocardial perfusion as disclosed by pharmacologic stress testing using cardiac magnetic resonance (CMR) imaging in an ongoing community-based study of persons initially without a history of coronary heart disease (CHD)[1].

Of the 1066 participants of the Multi-Ethnic Study of Atherosclerosis (MESA), 22% agreed to be examined by CMR imaging at both rest and during myocardial hyperemia caused by adenosine-induced coronary vasodilation. Global myocardial blood flow as well as perfusion reserve (the difference between myocardial flow at rest and during pharmacologic stress) were significantly diminished with increasing age and among men as compared with women, according to Dr Lu Wang (University of Minnesota, Minneapolis) and associates. None of the participants showed focal perfusion defects.

What is quite remarkable is that age and gender had such a strong effect.

"The significantly higher myocardial blood flow and perfusion reserve found in our female participants without obstructive CHD remained even when menopause status and hormone use were considered, which suggests that the gender difference may not be completely explained by a direct effect of estrogen," according to the group.

Other risk factors that emerged as significant correlates of reduced myocardial flow included diastolic blood pressure, total cholesterol, and low-density-lipoprotein cholesterol, Wang et al write in the February 7, 2006 issue of the Journal of the American College of Cardiology.

Even when some functional tests show normal ventricular wall motion and localized hypoperfusion can't be seen in radionuclide or other standard perfusion scans, CMR rest-stress imaging can detect signs of preclinical disease, observed coauthor Dr Michael Jerosch-Herold (Oregon Health and Science University, Portland). "What is quite remarkable is that age and gender had such a strong effect," he told heart wire , observing that impaired perfusion reserve sends a stronger prognostic message in younger people than in older ones. That diabetes wasn't closely correlated with myocardial perfusion was a surprise, one that is probably explained by the MESA study's small diabetic subgroup, he said.

Significance for adjusted correlations between selected CHD risk factors and hyperemic myocardial blood flow and coronary perfusion reserve

Risk factor p,hyperemic blood flow p, perfusion reserve
Age <0.0001 <0.0001
Men (vs women) <0.0001 0.03
Hypertension (vs no hypertension) 0.08 0.01
Diastolic BP 0.05 0.03
Diabetes (vs no diabetes) 0.81 0.51
Total cholesterol 0.04 0.005
LDL cholesterol 0.12 0.04
Adjusted for age, sex, and race. Risk factors as continuous variables except as noted.
CHD=coronary heart disease
BP=blood pressure
LDL=low-density lipoprotein
Other risk factors with nonsignificant relationships to both perfusion measures included ethnicity, smoking status, body weight, physical activity, systolic blood pressure, and high-density-lipoprotein cholesterol

Whereas other investigations of myocardial-perfusion markers in asymptomatic persons have tended to focus on individual predictors such as diabetes or dyslipidemia, according to Jerosch-Herold, the MESA analysis assembled a range of standard ones and found that the severity of flow impairment went up with increasing risk-factor burden. The current study also stands out from others because it used CMR instead of positron-emission tomography, a less widely available myocardial-perfusion imaging technology, he said.

The analysis didn't consider event rates and their relationship to perfusion findings, so it says nothing about myocardial blood-flow scans as a screening tool, observed Jerosch-Herold. But he said the MESA investigators plan to study that issue as more outcomes from the cohort become available.


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