スタディにより一般人口における"無症状"の心発作有病率を調査する

認識されていないMI患者の多くにおいて、心電図検査や臨床評価から心筋瘢痕は検出されない
Myocardial scars not detected by electrocardiography or clinical evaluation for most people with an unrecognized MI
多人種の中年以降を対象としたスタディにおいて、心筋瘢痕保有率は約8%であったが、そのうち約80%は心電図検査や臨床評価では認識されなかった、と2015年American Heart Association学会で発表されJAMAに掲載された。研究者らは心臓磁気共鳴画像（CMR）を用いて心筋瘢痕保有率を調査した。参加者は多人種、スタディ開始時の2000～2002年に45～84歳であり、臨床上の心血管疾患（CVD）は有していなかった。10年後（2010～2012年）の調査において、参加者1,840人（平均年齢 68歳；男性52%）が心筋瘢痕検出のためガドリニウムを用いたCMR画像検査を施行された。スタディ開始時および10年後に心血管疾患リスクファクターおよび冠動脈石灰化（CAC）スコアが計測された。CMRにより検出された心筋瘢痕保有率は7.9%（1,840人中146人）であった。これまで認識されていなかった心筋瘢痕は6.2%であり、1.7%は臨床的に認識されたMIであった。したがって、78%（146人中114人）の心筋瘢痕は臨床的また は心電図（ECG）評価では認識されなかった。男性の方が女性よりも心筋瘢痕保有率が高かった（12.9%対2.5%）。
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In a multiethnic, middle-aged and older study population, the prevalence of myocardial scars was nearly 8 percent, of which nearly 80 percent were unrecognized by electrocardiography or clinical evaluation, according to a study in the November 10 issue of JAMA. This issue, a cardiovascular disease theme issue, coincides with the American Heart Association's Scientific Sessions 2015.

Ischemic heart disease is an important public health concern, but a considerable proportion of myocardial infarctions (MIs) are clinically unrecognized. Given the aging population, it is important to understand the prevalence, risk factors, and prognosis of unrecognized MI. In patients who survive an MI, normal contractile tissue is replaced by noncontractile fibrosis. Myocardial scarring leads to abnormal heart function and poor prognosis. The prevalence of and factors associated with unrecognized MI and scar have not been previously defined using contemporary methods in a multiethnic U.S. population, according to information in the article.

David A. Bluemke, M.D., Ph.D., of the National Institute of Biomedical Imaging and Bioengineering, Bethesda, Md., and colleagues examined the prevalence of myocardial scar using cardiac magnetic resonance (CMR; considered a standard of reference for defining the presence of myocardial scar). Participants were multiethnic, 45 through 84 years of age and free of clinical cardiovascular disease (CVD) at study entry in 2000-2002. In the 10th year examination (2010-2012), 1,840 participants (average age, 68 years; 52 percent men) underwent CMR imaging with gadolinium to detect myocardial scar. Cardiovascular disease risk factors and coronary artery calcium (CAC) scores were measured at study entry and year 10.

The overall prevalence of myocardial scar by CMR was 7.9 percent (146 of 1,840). The prevalence of previously unrecognized myocardial scar was 6.2 percent, whereas 1.7 percent had clinically recognized MI. Thus, 78 percent (114 of 146) of myocardial scars were unrecognized by clinical or electrocardiography (ECG) evaluation. Men had a higher prevalence of myocardial scar than women (12.9 percent vs. 2.5 percent).

Of individual risk factors, age, male sex, CAC score, body mass index, current smoking, and use of antihypertensive medications at study entry were associated with higher odds of myocardial scar.

"The clinical significance of unrecognized myocardial scar remains to be defined, although prior myocardial scar has been noted pathologically in more than 70 percent of patients with sudden cardiac death but without prior known coronary artery disease," the authors write. "Further studies are needed to understand the clinical consequences of these undetected scars."