Patients with acute myocardial infarction (AMI) with low body mass index (BMI) have worse outcomes than obese patients, and this phenomenon is recognized as "obesity paradox." Coronary calcification is associated with cardiac events. However, the association between BMI and calcification and their involvement in the mortality of AMI patients remain unknown. This study consecutively enrolled 517 patients with AMI who underwent emergent coronary intervention within 24 h after onset. Patients were divided into four groups according to the baseline BMI interquartile ranges: Q1 (BMI < 21.9 kg/m2), Q2 (21.9 ≤ BMI < 24.0 kg/m2), Q3 (24.0 ≤ BMI < 26.0 kg/m2), and Q4 (BMI ≥ 26.0 kg/m2). Calcification in the culprit lesion was also evaluated. The Q1 group was older and had a lower frequency of coronary risk factors. Moderate/severe calcification was most frequently observed in Q1, followed by Q2, Q3, and Q4. The Q1 group had the highest all-cause mortality, and patients with moderate/severe calcification had a higher all-cause mortality than that in patients without calcification. The highest all-cause mortality was observed in Q1with calcification, and the lowest was in Q4 without calcification. Q1 and the presence of moderate/severe calcification were independently associated with all-cause mortality. Although low-BMI patients with AMI had a lower frequency of coronary risk factors, they had a worse all-cause mortality than that in high-BMI patients. Our findings suggest that lesion calcification and its possible association with low BMI are involved in the higher mortality rate in these patients.
Keywords: Acute myocardial infarction; Body mass index; Coronary calcification.