Abstract 16205: Prevalence and Prognosis of Unrecognized Myocardial Infarction by Cardiac Magnetic Resonance versus ECG in the ICELANDMI Study
Background: We compared the ability of late gadolinium enhancement cardiac magnetic resonance (CMR) and electrocardiography (ECG) to diagnose unrecognized myocardial infarction (UMI) and to predict mortality in an older, community based sample in Iceland. We hypothesized that CMR would detect more UMI than ECG and that UMI by CMR would have prognostic significance.
Methods and Results: The ICELAND MI substudy of the Age, Gene/Environment Susceptibility (AGES) Study randomly recruited 675 participants; an additional 275 subjects with diabetes were also recruited. Of 936 subjects (age 67-94 yrs) receiving ECG and CMR scans, 49% were male, and 37% were diabetic. Subjects were defined as having unrecognized MI when there was evidence of MI by either ECG criteria (Minnesota codes 1.1.1-1.2.8) or by CMR, respectively, but there was no evidence of prior MI by patient records or by surveillance records. The prevalence of UMI was higher by CMR than ECG (19% vs. 5.4%, p<0.001). The prevalence of any MI detected by CMR was higher than any MI detected by ECG (24% vs. 7.5%, p<0.001). Over a median follow-up period of 4.9 years, 116 (12%) subjects died. Among those without recognized MI, UMI by CMR was associated with mortality (HR 1.79, 95%CI 1.14-2.80; age-adjusted HR 1.58, 95%CI 1.03-2.48) but UMI by ECG was not (HR 0.70, 95%CI 0.26-1.91). Any MI detected by CMR was associated with mortality, (HR 1.85, 95%CI 1.26-2.72), but any MI detected by ECG was not (HR 1.18, 95%CI 0.62-2.26). Kaplan-Meier curves for those without MI, those with unrecognized MI by CMR, and those with clinically recognized MI are shown (Figure).
Conclusions: The burden of unrecognized MI by CMR is higher than clinically recognized MI, and CMR is more sensitive for UMI detection than ECG. UMI detected by CMR carries a mortality risk similar to clinically recognized MI, supporting the need to identify individuals at risk and develop intervention strategies.
- © 2011 by American Heart Association, Inc.