Recognizing Unrecognized Risk

The rapid evolution of advanced cardiac imaging technologies has resulted in enhanced detection of subclinical disease with the potential for early implementation of therapeutic strategies and reduction in subsequent morbidity and mortality. Noninvasive assessment of ventricular function can provide evidence of prevalent coronary artery disease and cardiomyopathy and could supplant electrocardiography (ECG), the traditional marker of unrecognized myocardial infarction (UMI), in population screening. An appreciation of past efforts in this field is useful in understanding the potential future trajectories of these technologies.Article p 143 Ever since Herrick’s initial description of classic angina in 1912, it has been known that incident myocardial infarction (MI) will go unrecognized in a substantial portion of the population. Patients with UMI either recall symptoms that are atypical of MI or have no recollection of any event at all. Initially, autopsy findings and, later, ECG evidence indicated that “silent” MIs were frequent in hospitalized populations. These observations were later extended to a free-living cohort with the first epidemiological data reported from the Framingham Heart Study in 1959 by Stokes and Dawber.1 These investigators noted that 21% of subjects with new ECG-documented MI on biennial serial examinations had either atypical symptoms that were not clearly related to MI or no apparent ischemia-related complaints. Kannel and Abbott2 later observed that new Q-wave infarctions detected on biennial Framingham examinations over a 30-year follow-up period were unknown to 28% of the men and 35% of the women who experienced them, with approximately half of these MIs unaccompanied by discernible symptoms on further investigation. More impressive still was the fact that after MI diagnosis, the 10-year death rate was at least as great in subjects with UMI as in those with recognized infarction (45% versus 39%). As shown in the Table, these results have been confirmed by …