CORRESPONDENCE: LETTER TO THE EDITOR
Lack of Prognostic Impact of Elevated Troponin Levels in Patients Without Coronary Artery Disease
David Leibowitz, MD, FACC*
* Hadassah University Hospital, Coronary Care Unit, Mount Scopus, Jerusalem, Israel (Email: oleibo{at}hadassah.org.il).
The study by Dokainish et al. (1) addresses an interesting subgroup of patients with acute coronary syndromes (ACS), namely those with elevated troponin but without significant coronary artery disease (CAD) on angiography. The investigators conclude that a 6.3% incidence of death, reinfarction, and rehospitalization in this subgroup suggests an adverse prognosis as compared to the subgroup without significant CAD and negative troponin.
It is important to note that the figure of 6.3% is based on a total sample size of 32 patients. There were two adverse events in this group including one death and one rehospitalization. The researchers do not report whether these events were cardiovascular or not, information with clear implications for their conclusions. Even if these two events were cardiovascular, the tiny sample size severely limits the conclusions that can be drawn. It is also possible that the bias of knowledge of previous elevated troponin influenced the decision making in the single patient who was rehospitalized.
In addition, data from Table 1 of the Dokainish et al. (1) study demonstrate 9.4% of patients with positive troponin levels and no CAD had a history of congestive heart failure (CHF) as opposed to 2.7% of troponin-negative and no-CAD patients. A p value is given only for comparison across all four subgroups. No statistical comparison is made for the presence of CHF between the two subgroups of patients without CAD, nor is multivariate analysis available. It is possible that this finding influences the prognosis in this subgroup, without direct relation to the finding of elevated troponin. The finding of elevated B-type natriuretic peptide (BNP) as demonstrated in Table 2 (1) in the troponin-positive, CAD-negative group supports this contention.
In summary, far larger studies with correction for CHF, elevated BNP, and left ventricular function are necessary to truly assess the prognosis of patients with ACS with elevated troponin and nonsignificant CAD.
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1. Dokainish H, Pillai M, Murphy SA, et al. Prognostic implications of elevated troponin in patients with suspected acute coronary syndrome but no critical epicardial coronary disease: a TACTICS-TIMI-18 Substudy J Am Coll Cardiol 2005;45:19-24.[Abstract/Free Full Text]
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