Gender-Based Analysis of the 3-Year Outcome of Bioactive Stents Versus Paclitaxel-Eluting Stents in Patients with Acute Myocardial Infarction: An Insight from the TITAX-AMI Trial
- Volume 24 - Issue 3 - March 2012
- Posted on: 2/29/12
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Indeed, the trend toward a higher primary composite endpoint of MACE in the female subgroup was fundamentally driven by a trend toward higher TLR rates. Higher reintervention rates in female patients may be chiefly attributed to a significantly smaller reference vessel diameter in this subgroup, accounting for higher restenosis rates, ultimately causing further symptom-driven coronary angiography. Actually, within the female subgroup, TLR rate was numerically higher — albeit statistically insignificant — in patients assigned to receive BAS versus those assigned to receive PES (P=.29). Total MACE, however, and its two other components were better — again although statistically insignificant — in those who received BAS. It is noteworthy that among the male subgroup, total MACE, cardiac death, recurrent MI, and ST rates were all significantly better with BAS (P<.05 for all); TLR rate was better, but without meeting statistical significance.
In the trial arm that received BAS, the rate of total MACE was higher in females as compared with their male counterparts, obviously driven by a significantly higher rate of TLR. Once again, this may be viewed in light of the smaller-sized vessels in these patients, rather than any influence of gender, per se, on outcomes. Given the nearly similar gender-based rates of MACE and TLR in the arm that received PES, higher TLR in females who received BAS probably underlies the trend toward increased TLR in the female population as a whole. Albeit lower in the BAS group as compared with the PES group, the rate of cardiac death among patients who received BAS trended to be higher in females versus males, mostly driven by a trend toward a higher rate of ST in this particular subgroup. Although lower stent diameter, and quite possibly BAS undersizing, in the female subgroup might have contributed to the higher ST rates from a hypothetical perspective; the precise mechanisms underlying this surprising outcome are far from clear, and may leave a whole avenue for future research.
Independent predictors of outcome. Multivariable logistic regression analysis did not identify female gender among the independent predictors of MACE at 3-year follow-up. Instead, smaller stent diameter (again speaking of smaller coronary vessels), prior surgical revascularization, and allocation to PES independently predicted outcome. This makes a strong case for the theme that the divergence in outcome between the two gender subgroups most probably reflects differences in the nature of the underlying coronary disease, later presentation in life, and variance of comorbidities, rather than an influence of gender per se.
Study limitations. The TITAX-AMI trial was not designed to particularly explore gender-specific differences in outcome, whether as a pooled gender-based analysis or as regards gender and type of stent implanted. Furthermore, as already stated earlier, due to the retrospective nature of this post-hoc analysis, some data relevant to the outcome of PCI may have been missed. In addition, the trial may have been underpowered for specific subgroup analysis; therefore, any conclusions drawn from the analysis data should be taken with caution.