Diabetic heart disease and interventional cardiology: how can clinical outcomes be improved? Revascularization guided by hemodynamic parameters (fractional flow reserve).

Diabetes mellitus (DM) is an increasingly common disease, with an estimated prevalence of greater than 15% worldwide. Patients suffering from DM experience an increased risk of coronary heart disease, with a concomitant raise in cardiovascular morbidity and mortality. Accordingly, these patients represent 20%-30% of those undergoing revascularization procedures worldwide. Advances in the safety and technical success of percutaneous coronary intervention (PCI), along with preferences for less invasive methods have catalyzed a significant increase in PCI among patients with DM. However, DM represents a complex milieu for management of coronary heart disease, with known physiological effects including endothelial dysfunction, a prothrombotic state, and an increased pace of atherosclerotic plaque development. These features, and DM itself, confer an augmented risk of adverse cardiovascular outcomes. Multivessel disease is common among diabetic subjects with coronary artery disease, and leads to the consideration of an optimal revascularization strategy. Few studies have investigated the difference in outcomes between PCI and coronary artery bypass grafting (CABG) specifically in patients with DM. To date, the largest trial devoted to studying revascularization in patients with DM and multivessel disease is the FREEDOM trial 1 (Future Revascularization Evaluation in Patients With Diabetes Mellitus: Optimal Management of Multivessel Disease); it is a randomized-controlled trial that compares the outcomes of PCI versus CABG in patients with DM and multivessel disease. In this trial, patients with DM requiring revascularization with angiographically proven multivessel disease, and lesions amenable to either PCI or CABG were randomized to complete coronary revascularization using 1 of these techniques. The primary outcome (all cause mortality, nonfatal myocardial infarction [MI], and nonfatal stroke) at 5 years was more common among patients treated with PCI than with those treated with CABG (26.6% vs 18.7%, P=.005). Among individual components of the primary outcome, there was a significantly increased long-term risk of all cause mortality and nonfatal MI with PCI as compared to CABG. CABG, however, was associated with an increased risk of nonfatal stroke. The severity of strokes in the CABG group was also found to be twice as likely to severely disable the patient as compared to strokes occurring in the PCI group. The FREEDOM trial 1 largely validates smaller studies, subgroup analysis, and meta-analysis attempting to compare methods of revascularization in diabetic patients with multivessel disease. The CARDia (Coronary Artery Revascularization in Diabetes trial) randomized trial comparing PCI to CABG, while smaller in size, was also dedicated to patients with diabetes, with a significant fraction of the diabetics suffering from multivessel disease. 2 Although this study was terminated early due to lack of funding, it showed no significant difference in 1-year mortality. Like the FREEDOM trial, however, it revealed an increased risk of stroke in the CABG group. Concomitantly, while a majority of patients were treated with drug-eluting stents (DES) in this trial, there was a significantly increased need for repeat revascularization procedures with PCI. The SYNTAX trial (Synergy Between Percutaneous Coronary Intervention With TAXUS and Cardiac Surgery) randomized 1800 patients with multivessel or left main disease (1709 of these patients had multivessel disease) to PCI with DES versus CABG, and 30% of enrolled subjects had DM. 3 In the SYNTAX trial, complete revascularization was the goal for both study groups, and the average number of treated vessels and stents among patients with PCI for left main disease or mulitvessel disease was 3.6