Coronary artery disease treatment in diabetics

Patients with diabetes are more likely to have coronary artery disease (CAD) than non-diabetic patients. Furthermore, they are more likely to have multivessel disease, and they more commonly present with atypical anginal symptoms, or even silent ischemia. Diabetic patients with CAD have lower long-term survival rates than non-diabetic patients with CAD.

The main goal of treating diabetic patients with CAD is to decrease long term rates of death. It is important to carefully select those patients who would benefit from revascularization, and then to determine whether PCI or CABG is the preferred strategy. Among patients who undergo revascularization therapy, the major goal is to prolong their event-free survival time.

Strategies that include aggressive risk factor modification such as glycemic control with a target HbA1C less than 7, LDL less than 100 mg/dl, blood pressure lower than 130/80, smoking cessation, weight loss and regular exercise, showed no significant difference in the rates of death and major cardiovascular events compared to prompt revascularization at 5 years of surveillance for stable ischemic heart disease.

Medical treatment is a non-invasive treatment option which has shown similar outcomes at 5 years of surveillance for diabetic patients with stable ischemic heart disease when compared to PCI and CABG.

Initial procedural success is similar in both patients with diabetes and those without; however, diabetic patients have higher rates of restenosis and lower rates of event-free survival than non-diabetic patients. This is thought to be secondary to progression of disease in untreated areas and restenosis in treated areas.

After bare metal stent (BMS) placement, diabetic patients are more likely to have a decrease in event-free survival at 1-year with an increase in both overall and cardiac mortality. These same findings were consistent in studies with longer follow-up periods where diabetic patients had a higher incidence of mortality and need for repeat revascularization.

Drug-eluting stents (DES) are now used preferentially over BMS in most patients because they are associated with marked reductions in the incidence of restenosis and target lesion revascularization. At 4-year follow-up in the TAXUS trial^[1], treatment of diabetic patients with paclitaxel-eluting stents (PES) compared with BMS was safe and effective, resulting in markedly lower rates of target lesion revascularization, with similar rates of death, myocardial infarction, and stent thrombosis. As showed in several trials, such as SIRIUS^[2] and SCORPIUS^[3], diabetic patients treated with sirolimus-eluting stents (SES) had better outcomes with a significantly lower rate of target lesion revascularization, decreased late luminal loss, and major adverse cardiac events compared to those treated with bare metal stents. A meta-analysis comparing the clinical efficacy of drug-eluting stents in diabetic patients concluded that the revascularization and major adverse cardiovascular events estimates are similar with both PES and SES.^[4]

PCI is generally associated with less morbidity and mortality than CABG. Given the dramatically lower rates of restenosis with drug-eluting stents, this approach is good for patients with focal one or two vessel disease, as long as the proximal LAD or left main are not involved.

As with PCI, death, major adverse cardiac events, short and long-term outcomes tend to be worse in diabetic patients compared to non-diabetic patients. Outcomes with coronary artery bypass graft surgery are generally better than those treated with PCI or medical management, especially for multivessel disease and if there is involvement of the left anterior descending artery and an internal mammary artery is used.

While contemporary trials comparing revascularization with drug-eluting stents versus CABG in diabetic patients with multivessel disease are ongoing, the available data comparing PCI to CABG in this setting are in favor of CABG with regards to long term outcomes.

• In diabetic patients, intensive medical treatment should be considered if the patient has stable angina that is not significantly interfering with the quality of life or for whom the procedure is not indicated to prolong life.

• PCI with placement of drug-eluting stent(s) should be considered if the patient has:

• Single vessel disease
• Double vessel disease excluding the proximal LAD
• Older patients with significant comorbidities
• Prior CABG

• CABG (especially if an IMA can be used) should be considered if the patient has:

• Triple vessel disease
• Significant left main coronary artery stenosis
• Double vessel disease with one of the lesions being a proximal left anterior descending coronary artery lesion
• Significant coronary artery disease and also requires surgery for a heart valve

• Regardless of treatment choice, all patients should have aggressive risk factor modification as well (i.e. blood pressure control, lipid control, tobacco cessation, weight loss, regular exercise and blood sugar control).

Resolution of both symptomatic and asymptomatic ischemia.

If a patient had angina or ischemia despite optimal medical management, revascularization should be considered. Also, if a patient has angina after having CABG, PCI with placement of drug-eluting stent(s) should be considered. Furthermore, if a patient fails PCI, either through initial technical failure or repeated episodes of restenosis, they should be considered for CABG– especially if an IMA can be used.

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