Prevalence and Correlates of Myocardial Scar in a US Cohort

Abstract

Importance 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. Objective 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. Exposures Cardiovascular risk factors, coronary artery calcium, left ventricle size and function, carotid intima media thickness Main Outcome Measure Myocardial scar detected by CMR. Results 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.

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“…This rigorous screening allowed us to better isolate the effect of exercise training per se, from the confounding effects of other co-morbidities. In fact, the prevalence of LGE in the present cohort was lower than reported in the general population, 34 likely due to the absence of cardiovascular disease risk factors. The lack of association of lifelong high endurance exercise with areas of focal myocardial fibrosis, especially in individuals with youthfully compliant hearts as assessed directly by invasive measures lends support to the concept that the ‘athlete's heart’ is most commonly a reversible physiological adaptation and not a pathological substrate for malignant arrhythmias or a precursor to cardiovascular death.…”

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“…27 More recently, in the MESA study, unrecognized scar was reported in 6.2% of participants of whom 62% were classified as “atypical” for myocardial infarction. 18 The prevalence of scar in the current study was slightly different from the prior publication as individuals with an incident HF event prior to exam 5 were excluded in the present analysis. The lower prevalence of LGE, and particularly “typical” scar compared with prior non-MESA general population studies is likely based on the initial exclusion in MESA of known CVD, the race/ethnic heterogeneity of the cohort (with whites having the highest prevalence of LGE) and younger age of MESA participants.…”

“…Myocardial scars predominantly affecting midwall or subepicardium without subendocardial involvement in a non-coronary artery distribution were defined as an “atypical” scar. 18 …”

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“…), 146 (7,9 %) osoba imalo je ožiljke miokarda. 27 U 78 % osoba ožiljci miokarda nisu bili prepoznati elektrokardiogramom ni kliničkom evaluacijom. Dob, muški spol, indeks tjelesne mase, arterijska hipertenzija i vrijednost CACS-a (prilagođena spolu, dobi i etničkoj skupini) pri prvom pregledu povezani su s prisutnošću ožiljaka miokarda nakon 10 godina.…”

“…30 Ispitanici s ranom prezentacijom dilatacijske kardiomiopatije, s obzirom na ispitanike koji se bave aerobnim aktivnostima više od 6 sati na dan, pokazali su znatno produženje participants in the MESA study who were free of clinical cardiovascular disease at baseline (in 2000-2002) and underwent LGE CMR in the 10 th year examination (2010-2012), 146 (7.9%) individuals showed myocardial scar. 27 In 78% of them, myocardial scar was unrecognized by electrocardiogram or clinical evaluation. Age, male sex, body mass index, hypertension, and CACS (adjusted for age, sex, and ethnicity) at baseline were associated with presence of myocardial scar at year 10.…”