Myocardial scarring leads to cardiac dysfunction and poor prognosis.
The prevalence of and factors associated with unrecognized myocardial
infarction and scar have not been previously defined using current methods
in a multi-ethnic US population.
To determine prevalence of and factors associated with myocardial
scar in middle and older aged individuals in the United States (U.S).
Design, Setting, and Participants
Multi-Ethnic Study of Atherosclerosis (MESA) is a population based
cohort in the U.S. MESA participants were 45-84 years old and free of
clinical cardiovascular disease (CVD) at baseline in 2000-2002. In the
10th year examination of MESA (2010-2012), 1840 participants
underwent cardiac magnetic resonance imaging (CMR) with gadolinium to detect
myocardial scar. CVD risk factors and coronary artery calcium scores were
measured at baseline and year 10. Logistic regression models were used to
estimate adjusted odds ratios for myocardial scar.
Cardiovascular risk factors, coronary artery calcium, left ventricle
size and function, carotid intima media thickness
Main Outcome Measure
Myocardial scar detected by CMR.
Of 1840 participants (mean age 68±9 yrs, 52% male),
146 had myocardial scars (7.9%). Most myocardial scars (114/146,
78%) were undetected by electrocardiogram or by clinical
adjudication. In adjusted models, age, male gender, body mass index,
hypertension, and current smoking at baseline were associated with
myocardial scar at year 10 [OR (95% CI): 1.6 (1.4, 1.9) per
8.9 years, p<0.001; 5.8 (3.6, 9.2) men vs. women, p<0.001;
1.3 (1.1, 1.6) per 4.8 kg/m2, p=0.005, 1.6 (1.1, 2.3) for
hypertension present, p=0.009; 2.0 (1.2, 3.3) current vs. never
smokers, p=0.006, respectively]. Age, gender and ethnicity
adjusted CAC score at baseline was also associated with myocardial scar at
year 10 [CAC categories of 1-99, 100-399 and ≥ 400 vs. CAC
=0: OR (95% CI): 2.4 (1.5, 3.9), 3.0 (1.7, 5.1), 3.3 (1.7,
6.1), respectively, p≤0.001]. CAC score significantly added
to the association of myocardial scar with age, gender, ethnicity and
traditional CVD risk factors (c-statistic: 0.81 vs. 0.79, with vs. without
CAC, respectively, p=0.012).
Conclusions and Relevance
The prevalence of myocardial scars in a US community based
multiethnic cohort was 7.9%, of which 78% were unrecognized
by electrocardiography or clinical evaluation. Further studies are needed to
understand the clinical consequences of these undetected scars and the
utility of their identification.