Study Design

This is a single-center retrospective study that enrolled patients from the Medicine, Angioplasty or Surgery Study (MASS) unit database at the Heart Institute of the University of Sao Paulo, Brazil. Patients with multivessel CAD (defined as stenosis ≥ 70% in at least 2 of the 3 main coronary arteries) and preserved LVEF who underwent coronary artery bypass grafting (CABG), percutaneous coronary intervention (PCI), or medical treatment (MT) between January 2002 and December 2015 were included in this study.

Data Collection and Criteria

SS and SSII were calculated by scoring all coronary lesions with a diameter stenosis ≥ 50%, in vessels with a diameter ≥ 1.5 mm, using the SS algorithm, which is described in full elsewhere. Two experienced clinical cardiologists and two interventional cardiologists blinded to clinical outcomes calculated the SS retrospectively for each patient. Clinical data were obtained from the medical records for the calculation of SSII. Intraobserver and interobserver variability for the SS were performed for 100 coronary angiograms according to the kappa [k] coefficient. Coefficients ranging from 0.21 to 0.40 are considered fair, from 0.41 to 0.60 moderate, from 0.61 to 0.80 substantial, and over 0.81 excellent. For ordinal variables, the weighted kappa coefficient was used to express the degree of agreement inter-observer and intra-observer. 

For the SS and SSII calculation of the MT group, we used the CABG group as a reference. This option assumed that surgery is the strategy that provides the most complete revascularization in patients with multivessel CAD. The residual SYNTAX Score (rSS) was calculated for each coronary lesion that was evaluated with the SS but was not treated. The coronary angiogram performed immediately after the percutaneous intervention or the surgical report of the CABG patients was used to calculate the rSS. For the MT group, the rSS is similar to the SS. A higher value of rSS suggests that more CAD lesions were untreated. Finally, patients were categorized within each score as low, intermediate, and high.

Treatment

Patients were categorized according to three coronary revascularization strategies: MT, PCI and CABG. Patients in the three groups received intensive secondary prevention with lifestyle and pharmacologic interventions, using “treat-to-target” algorithms. All patients were treated according to the current guidelines at the time of study enrollment. 

Among patients undergoing PCI, target-lesion revascularization was always attempted, and complete revascularization was performed as clinically appropriate. Subjects in the PCI group received plain bare metal stents (BMS), or drug eluting stents (DES), as available. A successful PCI was defined as a normal coronary artery flow or less than 20% stenosis in the luminal diameter after coronary stent implantation, as assessed by visual estimation of the angiograms before and after the procedure. Clinical success was defined as angiographic success plus the absence of in-hospital myocardial infarction (MI), emergency CABG, or death.  

CABG was performed in accordance with the best current practices. The use of cardiac extracorporeal circulation was defined at the discretion of the surgical team, but the surgical team had experience in both on-pump and off-pump surgery.  

Study Endpoints

The primary endpoint was death from any cause at 5 years. Secondary endpoint was major adverse cardiac and cerebrovascular events (MACCE), defined as the composite of all-cause death, MI, stroke, and subsequent coronary revascularization measured.