Methods

As a part of their routine surveillance, cardiac transplant recipients at Stanford University Medical Center undergo annual cardiac catheterization, including coronary angiography. Those with a significant coronary lesion (≥70% stenosis correlating with ischemia on stress testing and/or a fractional flow reserve <0.75) that can be treated by percutaneous coronary intervention (PCI) generally receive a stent. From 1997 to 2009 (6 years before and after the introduction of DESs), we identified consecutive cardiac transplant recipients who underwent stenting for de novo CAV and had ≥1-year data after their index PCI. A total of 34 patients receiving a total of 46 stents (27 DESs and 19 BMSs) for treatment of 38 lesion segments were identified. All patients before April 2003 received BMSs exclusively, and those after received DESs only. The baseline clinical characteristics, medications, rejection episodes, and procedural details were gathered retrospectively from the medical records and cardiac catheterization reports.

All PCIs were performed by interventional cardiologists at our hospital. The primary operator determined the choice of equipment and procedural technique. DESs used included sirolimus-eluting stents (Cypher, Cordis, Johnson & Johnson, Bridgewater, New Jersey) and paclitaxel-eluting stents (Taxus, Boston Scientific, Natick, Massachusetts). All patients received antiplatelet therapy with clopidogrel for the duration considered standard at stent implantation, and aspirin was given indefinitely.

The lesion details before and after the intervention and at follow-up were obtained using quantitative coronary angiography (QCA) by an investigator who was unaware of the type of stent used. Digital angiograms were analyzed with an automated edge detection computer analysis system (Quant32, Sanders Data, Palo Alto, California). The minimum luminal diameter and percentage of diameter stenosis were determined with the outer diameter of the contrast-filled catheter as the calibration standard. The percentage of diameter stenosis was calculated as the (reference diameter − minimum luminal diameter)/(reference diameter) × 100. The reference vessel diameter was calculated as the average of both the proximal and the distal reference diameter. The lesion length was measured as the distance from the proximal to the distal shoulder of the lesion. Late lumen loss was measured within the stent and was defined by the minimum luminal diameter at 1 year of follow-up minus the minimum luminal diameter immediately after the index PCI.

The end points of interest included angiographic late loss, in-stent restenosis, target lesion revascularization, target vessel revascularization, nonfatal myocardial infarction, allograft loss, stent thrombosis, and death at 1 year of follow-up. Binary restenosis was defined as stenosis >50% of the luminal diameter on follow-up angiograms. The definitions used for target lesion revascularization, target vessel revascularization, and stent thrombosis were all consistent with recommendations from the Academic Research Consortium. Nonperiprocedural myocardial infarctions were defined by any elevation in troponin associated with signs or symptoms of coronary ischemia. Allograft loss was defined as patients undergoing retransplantation. Death was divided into cardiac and noncardiac causes. Unwitnessed death was presumed to be cardiac, unless another etiology was determined.

Because patients might have received >1 stent, descriptive statistics were done on a per-lesion basis, except for clinical outcomes, which were on a per-patient basis. Continuous variables are reported as the mean ± SD and compared using the Student t test. Categorical variables are expressed as frequency (percentages) and compared using the chi-square or Fisher exact test. Statistical analysis was performed using Prism, version 4.0a (GraphPad Software, La Jolla, California). In all cases, p <0.05 was considered statistically significant.

Results

The baseline clinical characteristics are listed in Table 1 and were similar between the DES and BMS groups. Most patients in both groups were white men, with a mean age of 53 years in the DES group and 48 years in the BMS group. The cardiac risk factors were common in both groups, and twice as many patients in the DES group had diabetes; however, the difference was not statistically significant. Also, no difference was found in the incidence of previous myocardial infarction or PCI or the use of particular cardiac drugs, including statins, between the 2 groups. The use of immunosuppressive medications was not different between the 2 groups, nor was the mean number of years since transplantation or the incidence of previous rejection episodes. In the DES group, 8 of the 18 patients had had previous episodes of rejection (with 3 having multiple episodes). In the BMS group, 9 of the 16 patients had had previous episodes of rejection (with 4 having multiple episodes).

The most common indication for PCI was an incidentally noted, asymptomatic, high-grade lesion on coronary angiography, comprising 60% and 56% of DES and BMS implantations, respectively ( Table 2 ). PCI for acute coronary syndromes or heart failure accounted for most of the remaining indications, and no differences were found in the indications for PCI between the DES and BMS groups. Of the 27 DESs deployed, 19 (70%) were sirolimus eluting and the remainder were paclitaxel eluting. Only 2 lesions involved the left main coronary artery, and both were in the BMS group. In general, the lesion types were similar between the DES and BMS groups, although there were more type C lesions in the DES group than the BMS group.

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