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We appreciate Horton's concerns regarding the potential heterogeneity in mechanisms of myocardial ischemia and causes of elevated troponin level. However, for the purposes of this analysis only, Medicare beneficiaries with a discharge diagnosis of acute MI were included in the analysis. Furthermore, while we recognize that troponin level may be elevated in several other syndromes beyond acute coronary syndromes, troponin is the gold standard for the diagnosis of MI because of its superior specificity and sensitivity for myocardial damage and greater ability to risk stratify patients with ischemic myocardial necrosis. In 2000, a new definition of MI was proposed that emphasized the use of cardiac troponins as the preferred marker of myocardial necrosis in the context of ischemic symptoms in routine clinical practice. Based on substantial data, troponin measurement has also been included as a fundamental component of diagnosis and risk stratification of MI in the most recent revision of the American College of Cardiology/American Heart Association guidelines for the management of non–ST-segment elevation acute coronary syndromes. Given the significant burden of cardiovascular disease in our society and the substantial morbidity and mortality associated with acute coronary syndromes, our efforts should be focused on ways to identify high-risk patients with positive troponin status and to apply evidence-based, life-saving therapies in these patients rather than looking to ways to discount a positive troponin test result. Based on current data, positive troponin status is the sine qua non of an MI until proven otherwise.
Foody JM. Are Guideline-Based Therapies for Myocardial Infarction Generalizable to Troponin-Only Positive Patients?—Reply. Arch Intern Med. 2008;168(4):437. doi:10.1001/archinternmed.2007.121