Author + information
- James L Januzzi, MD (, )
- Thomas E MacGillivray, MD,
- Kent Lewandrowski, MD and
- Elizabeth Lee-Lewandrowski, MD
We appreciate the comments of Drs. Chen-Scarabelli and Scarabelli. We agree that the distinctly different release kinetics of creatine kinase-MB (CK-MB) and troponin T (TnT) allow for complementary information in certain settings, particularly that of reinfarction. Indeed, it has been suggested that CK-MB be considered the marker of choice for the detection of reinfarction (1).
Though it was not the purpose of our study (2)to compare the prognostic role of cardiac markers among patients undergoing cardiac surgery soon after acute cardiac myonecrosis, among our cohort of 224 patients, 58 had TnT data available preoperatively. Of these, 26 had a level ≥0.10 ng/ml (at the time the conventional upper limit of normal for myocardial infarction [MI]). No clear association between elevated preoperative TnT and adverse postoperative outcomes was noted, nor did the elevation of preoperative TnT obscure the markedly powerful prognostic ramifications of marked elevations of TnT in the postoperative setting, which were independently prognostic, irrespective of preoperative TnT levels. This may be because the magnitude of TnT release identifying patients at risk for impending postoperative complications was so significant at each time point (with mean levels among complicated patients reaching nearly 9 ng/ml), compared to the generally lower levels of TnT released in the setting of most acute coronary syndromes. Given the small number of patients with elevated preoperative TnT in our study, however, it is impossible to characterize conclusively the comparative value of cardiac markers in this situation.
We agree that for the unusual circumstance of urgent cardiac surgery in the setting of a recent large acute MI, a cardiac marker with shorter serum existence such as CK-MB might be preferable for postoperative biochemical risk stratification. Finally, as we and others have demonstrated, the “expected” magnitude of TnT release following cardiac surgery varies between different procedures, and not all patients undergoing cardiac surgical procedures are expected to release large amounts of TnT (2–4). An example of this would be coronary artery bypass grafting without cardiopulmonary bypass, which is associated with significantly lower amounts of postoperative TnT release (3,4). In such patients, significant elevations of preoperative TnT might obviate the use of this marker for postoperative risk stratification. Nonetheless, for many, if not most patients undergoing cardiac surgical procedures, we believe that postoperative measurement of cardiac TnT affords superior prognostic information.
- American College of Cardiology Foundation
- Alpert J.S.,
- Thygesen K.,
- Antman E.,
- Bassand J.P.
- Januzzi J.L.,
- Lewandrowski K.,
- MacGillivray T.E.,
- et al.
- Kathiresan S, MacGillivray TE, Lewandrowski K, et al. Off-pump coronary bypass grafting is associated with less myocardial injury than coronary bypass surgery with cardiopulmonary bypass. Heart Surg Forum 2003. In press