Successful revascularization of chronic total occlusions (CTOs) has been associated with clinical benefit. Data on outcomes in patients with previous coronary artery bypass grafting (CABG) undergoing percutaneous coronary intervention (PCI) for CTO, however, are scarce. A total of 2,002 consecutive patients undergoing PCI for CTO from January 2005 to December 2013 were divided into patients with and without previous CABG, and outcomes were retrospectively assessed. The primary outcome measure was all-cause mortality. Median follow-up was 2.6 years (interquartile range 1.1 to 3.1). A total of 292 patients (15%) had previous CABG; they were older and had a greater prevalence of comorbidities. Procedural success was achieved in 75% and 84% of patients in the previous CABG and the non-CABG groups (p <0.001), respectively. All-cause mortality was 16% and 11% in the previous CABG and the non-CABG groups (p = 0.002), and differences were mitigated after adjustment for baseline characteristics (adjusted hazard ratio [HR] 1.22, 95% confidence interval [CI] 0.86 to 1.74, p = 0.27). All-cause death was significantly reduced in patients with procedural success, both in the previous CABG (11% vs 32%, adjusted HR 0.43, 95% CI 0.24 to 0.77, p = 0.005) and the non-CABG groups (10% vs 20%, adjusted HR 0.63, 95% CI 0.45 to 0.86, p = 0.004), with similar mortality benefits associated with successful revascularization in both groups (interaction p = 0.24). In conclusion, the relative survival benefit of successful recanalization of CTO is independent of previous CABG. However, owing to a greater baseline risk, the absolute survival benefit of successful CTO procedures is more pronounced in patients with previous CABG than in non-CABG patients.
Chronic total occlusions (CTOs) continue to be a particularly challenging lesion subset associated with increased rates of procedural failure and complications. The prevalence of CTO in patients with previous coronary artery bypass grafting (CABG) is particularly high, and percutaneous coronary revascularization has emerged as promising treatment alternative to surgery when symptomatic bypass graft failure exists. Most studies have demonstrated that PCI for CTO in patients with previous CABG is associated with lower procedural success rates compared with that in patients without previous surgical revascularization, a finding that has mainly been attributed to the complex coronary anatomy and the heavily calcified lesions frequently encountered in these patients. However, data on clinical outcomes in patients with previous CABG are scarce and mostly limited to in-hospital events and rather small patient cohorts, and whether lower procedural success rates translate into worse outcomes in patients with previous CABG remains unclear. Given the increasing prevalence of patients with bypass graft failure, along with the implementation of novel interventional approaches, characterization and risk stratification of these patients gained further importance. The aim of this study was therefore to assess clinical and procedural characteristics as well as long-term outcomes in patients with and without previous CABG undergoing PCI for CTO.
Methods
Data from 2,002 consecutive patients who underwent elective PCI for CTO at our institution from January 2005 to December 2013 were collected from our clinical database and retrospectively assessed. The registry includes demographic, clinical, angiographic, and procedural data, along with in-hospital and long-term outcomes, of the patients. Patients were followed up by outpatient visits and telephone contacts performed at 30 days, 1 year, and 3 years after PCI for CTO. The indication for PCI for CTO was based on current guidelines on myocardial revascularization. PCI for CTO was performed with contemporary techniques including double injections and anterograde/retrograde techniques. CrossBoss and Stingray coronary (Boston Scientific Corporation; Marlborough, Massachusetts) CTO crossing and re-entry devices were not available. Coronary CTO was defined as angiographic evidence of a total occlusion with complete interruption of anterograde blood flow (Thrombolysis In Myocardial Infarction [TIMI] flow grade 0) with an estimated duration of ≥3 months (based on previous angiograms, angina symptoms, and a history of myocardial infarction). Procedural success was defined angiographically as complete restoration of anterograde blood flow (TIMI flow grade 3) and <30% residual diameter stenosis by visual assessment. The primary outcome measure was all-cause mortality. The secondary outcome measure was the cumulative incidence of major adverse cardiovascular events (MACE) including all-cause death, nonfatal myocardial infarction, and clinically driven target vessel revascularization. Nonfatal myocardial infarction was defined as the presence of new Q waves in ≥2 contiguous electrocardiographic leads or an elevation of creatine kinase level or its MB isoenzyme to at least 3 times the upper limit of normal in 2 plasma samples during hospitalization.
Continuous variables are presented as mean ± SD, or median and interquartile range, and categorical variables are given as frequencies and percentages. The Kolmogorov-Smirnov test was used to test for normality of distribution. Continuous variables were tested for differences with the unpaired Student t test or the Mann-Whitney U test and categorical variables with Pearson’s chi-square test or Fisher’s exact test as appropriate. Logistic regression and Cox proportional hazards models were used to assess adjusted risks of the outcome variables. Models were adjusted for selected variables significantly different between groups (p <0.05). Cox proportional hazards regression test of interaction (previous CABG/non-CABG status by procedural success/failure status) was used to assess whether there was a differential effect of procedural success by previous CABG/non-CABG status. Survival curves were generated with the Kaplan-Meier method, and the log-rank test was used to provide a formal statistical assessment of the differences between groups. A 2-sided p value of <0.05 was considered statistically significant. All statistical analyses were performed using IBM SPSS Statistics for Windows Version 21.0. (IBM Corp., Armonk, New York).
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