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
To the Editor:
With great interest, we read 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” by Li et al.1 Indeed, they are to be congratulated for their well-powered, multicenter, prospective, real-world study which concluded that antithrombotic therapy with subcutaneous enoxaparin plus periprocedural reduced-dose unfractionated heparin (UFH) (50 U/kg) in patients with acute ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention with drug-eluting stents showed a lower incidence of in-hospital cardiac and total death versus UFH alone. Eventually, this was translated into a reduction of 8-month mortality and major adverse cardiac events.1
Nevertheless, we were quite overwhelmed by the high rate of in-hospital death in the UFH group (cardiac and total death: 4.7% and 6.3%, respectively) that is far beyond the usual figures reported in literature.2, 3, 4, 5 As a matter of fact, the significantly higher death in this group at 8 months was chiefly driven by this unacceptably higher in-hospital mortality. Actually, the number of the cardiac deaths that occurred from hospital discharge to 8 months was surprisingly “lower” in the UFH as compared with the enoxaparin group: 16 (0.86%) versus 21 (1.37%), respectively; the number of total deaths was similar: 24 (1.3%) versus 24 (1.6%), respectively.1
In a trial to explain this high toll of in-hospital deaths and subsequently the higher “cumulative” mortality at follow-up, several issues have to be raised. First, the trial was not randomized; and this was clearly reflected by a significantly higher prevalence of prior myocardial infarction and congestive heart failure in the UFH group versus the enoxaparin group. Moreover, these patients received more calcium antagonists (versus the enoxaparin group), which may have further worsened their left ventricular systolic function (unreported in this study), a major determinant of short- and long-term outcome. The ʻgoldʼ standard in trial design for the comparison between 2 strategies is the prospective, randomized, controlled trial. Propensity-matched comparisons, by definition, contain differences in group characteristics. No adjustment, however meticulous, can correct for these multiple and often subtle differences. On the other hand, a well-designed randomized, controlled trial, through its design, obviates such a need.
References
- 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. 2010;159:684–690.e1
- Meta-analysis of randomized trials on drug-eluting stents vs 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
- Sirolimus-eluting versus uncoated stents in acute myocardial infarction. N Engl J Med. 2006;355:1093–1104
- 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
The author has no conflict of interest to declare.
PII: S0002-8703(10)00443-6
doi:10.1016/j.ahj.2010.06.002
© 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
