September 6th, 2012
Unrecognized MI: More Prevalent and Dangerous Than Previously Suspected
Unrecognized myocardial infarction is more prevalent, and is associated with a worse prognosis, than may be generally understood, according to a new study published in JAMA.
Studying a community-dwelling elderly (67-93 years of age) population in Iceland, Erik Schelbert and colleagues used ECG and cardiac magnetic resonance (CMR) to detect unrecognized MI. CMR was more effective than ECG at detecting unrecognized MI. The study established that unrecognized MI was twice as prevalent as recognized MI:
- No MI: 74%
- Recognized: 10%
- Unrecognized MI by ECG: 5%
- Unrecognized MI by CMR: 17%
Diabetics were more likely to have unrecognized MI detected by CMR than by ECG. After 6.4 years of follow-up, mortality was higher in the recognized and unrecognized MI groups than in the group without MI:
- Recognized MI: 33% (CI 23% to 43%)
- Unrecognized MI: 28% (CI 21% to 35%)
- No MI: 17%, (CI 15% to 20%)
After adjustment for other factors, unrecognized MI by CMR, but not by ECG, significantly improved risk stratification for mortality. People with unrecognized MI by CMR were less likely than people with recognized MI to take cardiac drugs.
According to the authors, the large percentage of unrecognized MIs has not been understood in the past due to previous reliance on ECG data; thus “a significant public health burden” has not been fully appreciated.