Risk of Hematologic Malignancies in Patients with Acute Myocardial Infarction: A Nationwide Population-Based Cohort Study

Background Acute myocardial infarction (AMI) mortality is particularly high in the early stages after an AMI event, whereas mortality from other causes is high in subsequent stages. Cancer is another leading cause of death, and as life expectancy is increasing, the number of patients with cancer is also increasing. AMI and cancer have several common risk factors including smoking, obesity, and comorbidities. As the life span of patients with AMI is increasing, there is growing interest in the incidence of cancer in these patients. A large population-based study revealed that patients with AMI had higher short- and long-term cancer incidence rates than those without a history of AMI. Nevertheless, there is a paucity of information regarding the association between AMI and risk of hematologic malignancies. In most studies, hematologic malignancies were analyzed as one subtype of cancer but not as a main outcome. In this nationwide population-based study, we aimed to examine the risk of hematologic malignancies in patients with AMI. Methods This study was a retrospective cohort study of 117,372 patients with AMI and without a history of hematologic malignancies, and 193,413 age- and sex-matched individuals with no history of AMI or hematologic malignancies diagnosed between January 1, 2003, and December 31, 2016. Data was obtained from the large Korean National Health Insurance claims database. We compared the cumulative hazard of hematologic malignancies between both groups using Kaplan-Meier estimates and log-rank tests. We also calculated the hazard ratio (HR) and 95% confidence interval (CI) using Fine and Gray's competing risk regression model, and death was considered as a competing risk. Results During the follow-up period (AMI, 8.15±4.10 years; control group, 15.54±4.10 years), 1,205 and 2,640 persons from the patient and control group were newly diagnosed with hematologic malignancies, respectively (1000 person-years incidence rate: 1.26% vs. 0.88%). After adjusting for all potential confounding variables, the risk of hematologic malignancies in the AMI group was 39% higher than that in the control group (adjusted hazard ratio [HR], 1.387; 95% confidence interval (CI), 1.247-1.543). These results were consistent in sensitivity and standardized incidence ratio (SIRs) analyses. SIRs were used to compare the incidence of hematologic malignancies in the study population (patients with AMI) with that in the general Korean population using cancer type, age, sex, and calendar year-specific incidence rates, as obtained from Statistics Korea (http://kosis.kr). Overall, the risk of all types of hematologic malignancies was higher in the AMI group than in the general population. Conclusions Patients with AMI have an increased risk of developing hematologic malignancies than persons without AMI. Active surveillance of newly occurring hematological malignancies after AMI should be considered.