Response to the letter regarding the article “Low-molecular-weight heparin versus unfractionated heparin in acute ST-segment elevation myocardial infarction patients undergoing primary percutaneous coronary intervention with drug-eluting stents”
Article Outline
We thank Drs Nammas and Hossam for their interest in our article1 and for raising some concerns. They suggested that the rate of in-hospital death in the unfractionated heparin (UFH) group is quite high (cardiac and total death: 4.7% and 6.3%, respectively) and is far beyond the usual figures reported in literature2, 3, 4, 5 and that the significantly higher death in this group at 8 months was chiefly driven by this unacceptably higher in-hospital mortality. We do understand their concerns about the high in-hospital mortality in the UFH group, but our study is different from the previously reported literature.2, 3, 4, 5 The present study was derived from a prospectively designed registry reflecting the real-world clinical practice in the era of drug-eluting stents. In the present study, we even enrolled patients with worse baseline characteristics including patients with advanced heart failure (Killip grade IV: 6.4% in the UFH group and 6.8% in the low–molecular-weight heparin group), which might have caused the higher rate of in-hospital mortality as compared with other previous randomized studies.2, 3, 4, 5 We totally agree with the opinion of Drs Nammas and Hossam that the criterion standard in trial design for the comparison between 2 strategies is the prospective, randomized, controlled trial. However, randomized trials are not always perfect because they usually have highly selected patients with relatively lower risk profiles treated in a nonroutine setting. Therefore, a multicenter registry study with larger study population such as our study may help to complete the picture gained from randomized trials.
As Drs Nammas and Hossam have mentioned, there was a statistically significant difference in the prevalence of prior myocardial infarction and congestive heart failure in the UFH group versus the enoxaparin group. Because of the nature of registry, there were some baseline biases between the 2 comparing groups. However, as shown in Table 1,1 there was a significantly higher incidence of heart failure on admission with Killip grades II and IV in the enoxaparin group as compared with the UFH group, suggesting that the low–molecular-weight heparin group might have higher prevalence of advanced heart failure at the time of enrollment. Furthermore, in the present study,1 despite higher use rate of calcium antagonists in the UFH group, the UFH group received more cilostazol, GP IIb/IIIa receptor blockers, β-blockers, angiotensin-converting enzyme inhibitors, and statins as compared with the enoxaparin group (Table 3). We suppose that these baseline biases might have been partly offset because of the more intensive pharmacologic support in the UFH group. Anyway, as we have mentioned in the section of limitations, we acknowledge that residual confounding factors might still persist even after we used propensity score to minimize the baseline biases. However, in some point of view, we think it may reflect the real effects of these 2 antithrombotics in the real-world clinical practice. Collectively, as suggested by Drs Nammas and Hossam, because of the limitations of registry study, further randomized study will be warranted to get definite conclusions.
References
- Li YJ, Rha SW, Chen KY, et al. Low-molecular-weight heparin versus unfractionated heparin in acute ST-segment elevation myocardial infarction patients undergoing primary percutaneous coronary intervention with drug-eluting stents. Am Heart J 159:684-690.e1.
- Sirolimus-eluting versus uncoated stents in acute myocardial infarction. N Engl J Med. 2006;355:1093–1104
- Meta-analysis of randomized trials on drug-eluting stents versus bare-metal stents in patients with acute myocardial infarction. Eur Heart J. 2007;28:2706–2713
- Randomized trial of Sirolimus-Eluting Stent Versus Bare-Metal Stent in Acute Myocardial Infarction (SESAMI). J Am Coll Cardiol. 2007;49:1924–1930
- Two-year clinical follow-up after sirolimus-eluting versus bare-metal stent implantation assisted by systematic glycoprotein IIb/IIIa inhibitor infusion in patients with myocardial infarction: results from the STRATEGY study. J Am Coll Cardiol. 2007;50:138–145
PII: S0002-8703(10)00444-8
doi:10.1016/j.ahj.2010.06.003
© 2010 Mosby, Inc. All rights reserved.
Refers to article:
- Low-molecular-weight heparin versus unfractionated heparin in acute ST-segment elevation myocardial infarction patients undergoing primary percutaneous coronary intervention with drug-eluting stents
- Low-molecular-weight heparin versus unfractionated heparin in acute ST-segment elevation myocardial infarction patients undergoing primary percutaneous coronary intervention with drug-eluting stents
