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Unrecognized MI more common, dangerous in older adults than previously suspected
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The prevalence of unrecognized MI by cardiac MRI was higher than that of recognized MI and was linked to an increased risk for death among older adults in Iceland, recent data indicate.
Unrecognized MI in older adults may have been previously underestimated due to the limitations of ECG, and more sensitive methods of detection, including cardiac MRI (CMR) with late gadolinium enhancement, may reveal higher prevalence, researchers wrote.
To evaluate the prevalence and mortality risk for unrecognized MI identified by CMR vs. ECG, the researchers examined 936 participants aged 67 to 93 years in ICELAND MI — a cohort substudy of the Age, Gene/Environment Susceptibility-Reykjavik study. Of those included in their analysis, 670 were randomly selected and 266 had diabetes.
Results showed that 9.7% of study participants had recognized MI, and 17% had unrecognized MI by CMR. The researchers found that CMR detected more unrecognized MI when compared with ECG (17% vs. 5%; P<.001), and participants with diabetes had more unrecognized MI detected by CMR than ECG (21% vs. 4%; P<.001). Data also indicated that, in the randomly sampled cohort, 9% had recognized MI, 14% had unrecognized MI by CMR and only 5% had unrecognized MI by ECG (P<.001). Further analysis linked unrecognized MI by CMR to atherosclerosis risk factors, coronary calcium, coronary revascularization and peripheral vascular disease.
During a median follow-up of 6.4 years, 33% participants with recognized MI and 28% with unrecognized MI by CMR died, which was significantly higher than the 17% of those without MI who died, the researchers said.
After adjustment for age, sex, diabetes and recognized MI, unrecognized MI remained associated with mortality (HR=1.45; 95% CI, 1.02-2.06), with an absolute risk increase of 8%. Unrecognized MI by CMR also significantly improved risk stratification for mortality, according to the researchers, although unrecognized MI by ECG did not (HR=0.88; 95% CI, 0.45-1.73), with an absolute risk increase of –2%.
Additionally, results indicated that participants with unrecognized MI by CMR used aspirin, beta-blockers and statin medications more than those with recognized MI.
“Less than one-third of those with [unrecognized MI] by CMR had prior revascularization to establish coronary disease and trigger secondary prevention strategies,” the researchers wrote. “Detection of [unrecognized MI] by CMR may provide an opportunity to optimize treatment for those vulnerable individuals, but further study is needed to assess this.”
For more information:
Schelbert EB. JAMA. 2012;308:890-897.
Disclosure: The researchers report no relevant financial disclosures.