Hirofumi Soejima1, Hisao Ogawa2, Takeshi Morimoto3, Sadanori Okada4, Mio Sakuma3, Masafumi Nakayama5, Izuru Masuda6, Naofumi Doi7, Shiro Uemura8, Hideaki Jinnouchi9, Seigo Sugiyama9, Masako Waki10, Yoshihiko Saito11. 1. Department of Cardiovascular Medicine, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan; Health Care Center, Kumamoto University, Kumamoto, Japan. 2. National Cerebral and Cardiovascular Center, Suita, Japan. 3. Department of Clinical Epidemiology, Hyogo College of Medicine, Nishinomiya, Japan. 4. Department of Diabetology and Department of Cardiovascular Medicine, Nara Medical University, Kashihara, Japan. 5. Nakayama Cardiovascular Clinic, Amakusa, Japan. 6. Takeda Hospital Medical Examination Center, Kyoto, Japan. 7. Department of Cardiovascular Medicine, Nara Prefecture Seiwa Medical Center, Ikoma-gun, Japan. 8. Department of Cardiovascular Medicine, Kawasaki Medical School, Kurashiki, Japan. 9. Department Internal Medicine, Jinnouchi Hospital Diabetes Care Center, Kumamoto, Japan. 10. Department of Internal Medicine, Shizuoka City Shizuoka Hospital, Shizuoka, Japan. 11. Department of Cardiovascular Medicine, Nara Medical University, Kashihara, Japan.
Abstract
BACKGROUND: Silent events with newly developed Q waves in electrocardiogram (ECG) [silent myocardial infarction (MI)] in diabetic patients is reported to be independently associated with an increased risk of fatal MI. However, the incidence rate of silent MI in diabetic patients has yet to be clarified. We sought to determine the incidence rate of first symptomatic MI and silent MI in diabetic patients. METHODS: We conducted a prospective cohort study on patients enrolled in the Japanese primary prevention of atherosclerosis with aspirin for diabetes (JPAD) trial which was started in 2002. It is a randomized controlled trial to examine the efficacy of low-dose aspirin therapy for the primary prevention of atherosclerotic events in type 2 diabetic patients. No patients had Q waves in their ECG before entry to the JPAD trial. We followed-up 1825 patients until July 2015 after completion of the JPAD trial in 2008. The median follow-up period was 10.3 years. We collected 1648 patients' ECGs to identify patients with silent MI. RESULTS: Symptomatic MI occurred in 65 patients and silent MI occurred in 22 patients. The incidence rate of symptomatic MI was 4.26 per 1000 patient-years and 1.44 for silent MI in diabetic patients. Thus, 25% of total MIs were silent. Cause-specific Cox proportional hazard model indicated that age (hazard ratio 1.06, 95% confidence interval; 1.03-1.10, p=0.0004) and long history of diabetes (1.00, 1.01-1.07, p=0.01) were independently associated with symptomatic MI, but these were not associated with silent MI. CONCLUSIONS: We demonstrated that incidence rate of first silent MI and that proportion of silent MI to all MIs was 25% in diabetic patients without a history of atherosclerotic events. Diabetic patients frequently need ECG screening for detection of silent MI.
BACKGROUND: Silent events with newly developed Q waves in electrocardiogram (ECG) [silent myocardial infarction (MI)] in diabeticpatients is reported to be independently associated with an increased risk of fatal MI. However, the incidence rate of silent MI in diabeticpatients has yet to be clarified. We sought to determine the incidence rate of first symptomatic MI and silent MI in diabeticpatients. METHODS: We conducted a prospective cohort study on patients enrolled in the Japanese primary prevention of atherosclerosis with aspirin for diabetes (JPAD) trial which was started in 2002. It is a randomized controlled trial to examine the efficacy of low-dose aspirin therapy for the primary prevention of atherosclerotic events in type 2 diabeticpatients. No patients had Q waves in their ECG before entry to the JPAD trial. We followed-up 1825 patients until July 2015 after completion of the JPAD trial in 2008. The median follow-up period was 10.3 years. We collected 1648 patients' ECGs to identify patients with silent MI. RESULTS: Symptomatic MI occurred in 65 patients and silent MI occurred in 22 patients. The incidence rate of symptomatic MI was 4.26 per 1000 patient-years and 1.44 for silent MI in diabeticpatients. Thus, 25% of total MIs were silent. Cause-specific Cox proportional hazard model indicated that age (hazard ratio 1.06, 95% confidence interval; 1.03-1.10, p=0.0004) and long history of diabetes (1.00, 1.01-1.07, p=0.01) were independently associated with symptomatic MI, but these were not associated with silent MI. CONCLUSIONS: We demonstrated that incidence rate of first silent MI and that proportion of silent MI to all MIs was 25% in diabeticpatients without a history of atherosclerotic events. Diabeticpatients frequently need ECG screening for detection of silent MI.