Real-world registry data support use of drug-eluting stents in diabetic patients

February 5, 2008 By Benjamin A. Olenchock, M.D. Ph.D. [mailto:bolenchock@partners.org]

Investigators in Italy have analyzed 2-year outcomes in diabetic patients who received a single drug-eluting (DES) or bare-metal stent (BMS) outside of the controlled trial setting. They found that major adverse cardiac events (MACE) were fewer in patients who received DES compared to BMS. This difference was due to a benefit in need for target vessel revascularization.

The Registro Regionale Angioplastiche dell’Emilia-Romagna (REAL) is a prospectively collected Web-based registry of percutaneous interventions (PCI) performed at 13 hospitals in central-northern Italy. The REAL registry was designed to collect data on real-world practices. Data from patients undergoing PCI for de novo lesions between July 2002 and December 2004 were analyzed, excluding patient with ST-elevation myocardial infarctions (MI) treated with primary PCI and patients who received greater than 1 type of stent. Lesion characteristics recorded in the registry are estimated by the interventionalist, and success is defined as TIMI 3 flow with less than 30% residual stenosis. Stent thrombosis was defined as angiographically documented complete occlusion or TIMI 1-2 flow in presence of a thrombus. Major adverse cardiac events were defined as all-cause mortality, non-fatal acute MI, or target-vessel revascularization.

There were 1648 diabetic patients who met eligibility criteria, most of whom received a BMS (n=1089). Comparisons between the DES and BMS group revealed few clinical differences and many expected differences in lesion characteristics. Patients who received DES were on average younger (66 vs. 69 years old), more were insulin-dependent (31% vs. 25%), and fewer had subacute ST-elevation MI (12% vs. 18%). Drug-eluting stents were used in lesions that were on average smaller in diameter (2.8 vs. 3.0 mm) and longer (18 vs. 15 mm). DES were more commonly used for lesions in the left anterior descending artery (53% vs. 33%), while BMS were more frequently used for lesions of the right coronary artery or or circumflex.

In unadjusted analyses, there was no difference in prespecified outcomes at 30-days. At one year and two years, however, MACE was lower in the DES arm (17% vs. 22%, p=0.019 at 1 year, 23% vs. 28%, p=0.014 at 2 years). To adjust for possible confounders, a propensity score analysis was performed, which adjusted for numerous clinical and lesion characteristics that could influence the likelihood of receiving one type of stent over another. The adjusted analyses revealed that the driving factor in the difference in MACE was due to lower incidence of target vessel revascularization in the DES arm (12% vs. 15% at 2-years, HR 0.66, CI 0.49-0.96, p=0.041). There was no difference in all-cause mortality (HR 0.94, CI 0.69-1.28, p=0.73). Interestingly, subgroup analysis revealed that the benefit of DES for improvement in need for target vessel revascularization was limited to non insulin dependent diabetics. There was no statistical difference in incidence of stent thrombosis at two years (1.5% in DES vs. 0.7% in BMS, p=0.176).

This real-world analysis of PCI outcomes in diabetics is one of the largest to date. The clinical trial data suggested that DES would reduce the need for revascularization by almost two-thirds, much more than 34% reduction seen in the real-world setting. The authors suggest that part of this difference might be due to higher estimates of restenosis in the trial setting due to protocol-driven angiography, more frequent use of thick-strut BMS in clinical trials, and perhaps less benefit of DES in high risk patients like diabetics or in more complex lesions that were not studied in the clinical trials.