Impact of Previous Percutaneous Coronary Intervention in Coronary Artery Bypass Grafting Outcome in Diabetic Patients.

01.01.08

G. Hossein Almassi, MD, FCCP
Steering Committee Member, Cardiovascular Medicine and Surgery NetWork

Summary of the article:
In the context of coronary artery disease, diabetes mellitus is a challenging risk factor for both the cardiologists and the cardiac surgeons, alike. Historically, diabetes mellitus has been associated with a worse outcome in patients undergoing percutaneous coronary interventions (PCI). Similarly, the results of coronary artery bypass grafting (CABG) in diabetic patients may not be as good as in nondiabetics. The issue of diabetic patients with prior PCI and stenting referred for subsequent coronary artery bypass grafting is an interesting one and raises the question of whether the results of CABG in this group of patients are any different from the diabetic patients with no prior PCI. A report from the group at the West German Heart Center Essen¹ in the August issue of the Journal of Thoracic and Cardiovascular Surgery provides interesting information in this regard.

From among 4,853 patients undergoing isolated, first-time CABG between January 2000 and March of 2006, 749 patients with diabetes mellitus were identified. These patients were divided into two groups:
Group 1: 621 patients without prior PCI.
Group 2: 128 patients with previous PCI.
The groups were similar in their demographics, except for a significantly higher number of patients with hypertension and preexisting renal disease in group 2. Also, more group 2 patients were receiving antiplatelet therapy before surgical intervention. The average time between the last PCI and surgery was 8 +/-11 months. In group 2, surgical indications identified by coronary angiography revealed isolated in-stent restenosis in 15%, isolated native coronary stenosis in 25%, and combined in-stent restenosis and native coronary stenosis in 60%; 72% had bare metal stents, 12% had drug-eluding stents, and 16% had both. The number of bypass grafts, cardiopulmonary bypass, and aortic cross-clamp time was similar in both groups.

Primary endpoint of the study was allcause in-hospital mortality. The secondary endpoint was major adverse cardiac events (MACE) rate, including preoperative myocardial infarction, low cardiac output syndrome, cardiac death, and sudden cardiac death during postoperative hospitalization. A propensity score matching was performed to control for selection bias.

Results of the study showed that the all-cause mortality was 2.9% in group 1 and 7.8% in group 2 (p=0.02). MACE was 6.1% in group 1 and 14.1% in group 2 (p=0.005). In addition, group 2 patients had a long ICU stay (p=0.04) and a higher incidence of rethoracotomy (p=0.02). In a multivariate logistic regression model, age and a history of previous PCI were independently associated with in-hospital death. Only a history of previous PCI was found to be an independent predictor for in-hospital MACE. With propensity score matching and a conditional logistic regression analysis, previous PCI was associated with an increased risk for in-hospital mortality (odds ratio 2.97, 95% CI, 1.12 to 7.86: p=0.028), and in-hospital MACE (odds ratio 2.46, 95% CI, 1.18 to 5.15: p=0.016).

The authors of this study concluded, "This study indicates that the practice of initial PCI before surgical intervention significantly increases the risk of subsequent coronary artery bypass grafting in a well-defined, risk-adjusted and propensity-score-matched subgroup of patients with diabetes mellitus and triple-vessel disease". The significance of prior PCI on outcome of subsequent CABG was recognized earlier in patients undergoing coronary angioplasty.² More recent data indicate that PCI itself adversely affects outcome both in patients undergoing repeated PCIs and in noncardiac surgical patients.^3-6 The findings of this study are in line with the American College of Cardiology/American Heart Association guidelines indicating superiority of CABG over PCI in patients with diabetes mellitus.

References

Thielmann M, Neuhauser M, Knipp S, et al. Prognostic impact of previous percutaneous coronary intervention in patients with diabetes mellitus and triple-vessel disease undergoing coronary artery bypass surgery. J Thorac Cardiovasc Surg 2007; 137: 470-476
Johnson RG, Sirois C, Watkins JF, et al. CABG after successful PTCA: a case control study. Ann Thorac Surg 1995; 59:1391-1396
Arjomand H, Willerson JT, Holmes J, et al. Outcome of patients with prior percutaneous revascularization undergoing repeat coronary intervention (from the PRESTO trial). Am J Cardiol 2005; 96:741-746
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