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Background— It is known that a significant number of patients experiencing an acute myocardial infarction have normal coronary arteries or nonsignificant coronary disease at coronary angiography (CA). Computed tomography coronary angiography (CTCA) can identify the presence of plaques, even in the absence of significant coronary stenosis. This study evaluated the role of 64-slice CTCA in detecting and characterizing coronary atherosclerosis in these patients. Methods and Results— Consecutive patients with documented acute myocardial infarction but without significant coronary stenosis at CA underwent late gadolinium-enhanced magnetic resonance and CTCA. Only the 50 patients with an area of myocardial infarction identified by late gadolinium-enhanced magnetic resonance were included in the study. All of the coronary segments were assessed for the presence of plaques. CTCA identified 101 plaques against the 41 identified by CA: 61 (60.4%) located in infarct-related arteries (IRAs) and 40 (39.6%) in non-IRAs. In the IRAs, 22 plaques were noncalcified, 17 mixed, and 22 calcified; in the non-IRAs, 5 plaques were noncalcified, 8 mixed, and 27 calcified ( P =0.005). Mean plaque area was greater in the IRAs than in the non-IRAs (6.1±5.4 mm 2 versus 4.2±2.1 mm 2 ; P =0.03); there was no significant difference in mean percentage stenosis (33.5%±14.6 versus 31.7%±12.2; P =0.59), but the mean remodeling index was significantly different (1.25±0.41 versus 1.08±0.21; P =0.01). Conclusions— CTCA detects coronary plaques in nonstenotic coronary arteries that are underestimated by CA, and identifies a different distribution of plaque types in IRAs and non-IRAs. It may therefore be valuable for diagnosing coronary atherosclerosis in acute myocardial infarction patients without significant coronary stenosis.

Background— It is known that 9% to 31% of women and 4% to 14% of men with acute myocardial infarction have normal coronary arteries or nonsignificant coronary disease at angiography. These patients represent a diagnostic and therapeutic challenge. Multislice computed tomography (CT) can noninvasively identify the presence of coronary plaques even in the absence of significant coronary artery stenosis. This study evaluated the role of 64-slice CT, in comparison with coronary angiography, in detecting and characterizing coronary atherosclerosis in patients with acute myocardial infarction without significant coronary artery stenosis. Methods and Results— Thirty consecutive patients with acute myocardial infarction but without significant coronary stenosis at coronary angiography underwent 64-slice CT. All coronary segments were quantitatively analyzed by means of coronary angiography (CA-QCA) and 64-slice CT (CT-QCA). Forty-seven (10.4%) of the 450 coronary segments were not evaluable by CT. The mean proximal reference diameters at CT-QCA and CA-QCA were, respectively, 2.88�0.75 mm and 2.65�0.9 mm; the overall correlation between CT-QCA and CA-QCA for quantification of reference diameter was r s =0.77; P s =0.11; P =0.03. Overall CT-QCA showed the presence of 50 plaques, of which only 11 were detected by CA-QCA. CT-QCA identified 25 plaques in infarct-related coronary arteries. Positive remodeling was present in 38 of the 50 plaques (76%), with a higher prevalence in the coronary plaques not visualized by CA-QCA (82.1% versus 54.5%). Conclusions— CT-QCA correlates well with CA-QCA in terms of coronary reference diameter analysis, but not stenosis quantification. Multislice CT can detect coronary atherosclerotic plaques in segments of nonstenotic coronary arteries that are underestimated by CA and may have an incremental diagnostic value for the diagnosis of acute myocardial infarction in patients without significant coronary stenosis at CA.

Background and objective Type 2 diabetes and increase in body mass index (BMI) are major risk factors for myocardial infarction. Recently the common variant rs9939609 in the fat mass and obesity-associated (FTO) gene was reported to associate with type 2 diabetes only through an effect on body mass index (BMI). In the present study we investigated whether rs9939609 variant in the FTO gene is directly associated with early-onset myocardial infarction. Method The Italian genetic study of early-onset myocardial infarction is a nationwide prospective case-control study involving 1842 patients hospitalised for a first myocardial infarction before the age of 45 years, and 1842 healthy subjects matched for age, gender and geographical origin. The following baseline data were collected for each case and control: age, gender, family history, body mass index, smoking habits, hypertension, hypercholesterolemia, diabetes, cocaine use, physical activity and alcohol consumption. Genotyping was performed using a Sequenome MassARRAY platform. Results The rs9939609 variant in FTO gene was significantly associated with early-onset myocardial infarction (odds ratio 1,25, 95% confidence interval 1.08 to 1.45; p=0.000015) with a multiplicative model of the effect. After adjusting for diabetes, BMI, hypercholesterolemia and smoking the rs9939609 risk allele was still significantly associated with early-onset myocardial infarction (odds ratio 1.20, 95% confidence interval 1.05–1.38; p=0.006), thus indicating that this variant has a direct effect on myocardial infarction, not mediated by BMI. As previously reported FTO genotype was also associated with an increase in BMI, more specifically the p-value of no association in the control group is equal to 0,01. Conclusions The rs9939609 variant in the FTO gene was significantly associated with the risk of early-onset myocardial infarction and with the increase in BMI. The rs9939609 variant in the FTO gene directly influences the risk of early-onset myocardial infarction.