Troponin-positive, MB-negative patients with non–ST-elevation myocardial infarction: An undertreated but high-risk patient group: Results from the National Cardiovascular Data Registry Acute Coronary Treatment and Intervention Outcomes Network–Get With Th

BackgroundDespite the 2000 and 2007 redefinition of myocardial infarction (MI), patients who are troponin (Tn) positive ([+]) but MB negative ([−]) may not be considered to have MI, particularly in the absence of known coronary disease (prior MI or revascularization; coronary artery disease [CAD]). How this affects treatment and outcomes has not been well described.MethodsDirect arrival patients with non–ST elevation MI (NSTEMI) enrolled in the American College of Cardiology NCDR ACTION-GWTG Registry were included. Patients missing marker data who were Tn (−) and had CAD were excluded. Troponin (+) patients were categorized as MB (+) (n = 11,563) or MB (−) (n = 4,501). Treatments and in-hospital outcomes were compared between the 2 groups using logistic regression.ResultsOf the 16,064 NSTEMI patients, 28% were MB (−). The MB (−) patients were older (median age 68 vs 65 years) and had more comorbidities (hypertension 71% vs 66%, diabetes 31% vs 27%, heart failure 22% vs 19%; all Ps < .01). After adjusting for baseline characteristics, MB (−) patients were significantly less likely to receive clopidogrel, antithrombins, glycoprotein IIb/IIIa antagonists, or angiography (all Ps < .001). In-hospital mortality was lower in MB (−) patients (3.8% vs 4.9%, P < .01), which remained significant after adjusting for baseline variables (odds ratio 0, 69, 95% CI 0.6-0.9, P = .002).ConclusionsPatients without known CAD who have NSTEMI and are MB (−) have a higher risk profile but are less likely to receive guideline-recommended acute pharmacologic treatment than those who are MB (+). Given the relatively high mortality in this group, increased emphasis on improving quality of care in Tn (+)/MB (−) patients is warranted.