Interventional SYNTAX Scoring in a Patient With Diabetes | Patient Case Quiz

A 57-year-old Caucasian man presents to the cardiology clinic complaining of worsening symptoms of dyspnea on exertion and fatigue for the last six weeks. He has a history of insulin-dependent diabetes mellitus, hypertension (HTN), and dyslipidemia. There is no history of tobacco or alcohol use. Family history is significant for diabetes mellitus and HTN in both parents as well as fatal coronary artery disease (CAD) in his father.

He is married, works in the library of the local university, and spends a great amount of time sitting at a desk. He tries to be sensible about his diet, but does admit that his "diabetes has not been under the best control." He does not participate in any regular exercise, but was able to walk up two flights of stairs without difficulty until the last six weeks. On exam, blood pressure is 157/85 mm Hg, body mass index (BMI) 29 kg/m2, and waist circumference 118 cm. The rest of the physical examination is normal. The laboratory studies show total cholesterol of 230mg/dL, high-density lipoprotein cholesterol (HDL-C) 28 mg/dL, triglycerides 158 mg/dL, and HbA1c 7.9%.

Given his symptoms, the patient undergoes a nuclear myocardial perfusion stress testing. The study reveals a moderate area of inferior ischemia and mild distal anterior and apical ischemia. He subsequently undergoes cardiac catheterization. His coronary angiogram reveals 80-90% mid right coronary artery (RCA) stenosis, 50-70% proximal left circumflex (LCX) stenosis, and 50-70% stenosis of the mid left anterior descending coronary artery (LAD) and diagonal branch. Given the possibility of significant LAD and LCX disease, fractional flow reserve (FFR) measurements are performed on the LAD and LCX. Fractional flow reserve (FFR) of the LAD is 0.72, and LCX is 0.76 (anything less then 0.80 is felt to be physiologically significant). This suggests that he has significant three-vessel CAD involving the RCA, LAD, LCX (Figure 1). However, all lesions are angiographically focal in appearance (and without significant tortuosity or calcification), and his calculated SYNTAX score is approximately 16.1 The cumulative four-year major adverse cardiac and cerebrovascular event rate (MACCE) rate for this SYNTAX score is approximately 28% for coronary artery bypass graft (CABG) or percutaneous coronary intervention (PCI) (score for all patients and not specifically for patients with diabetes) for revascularization via either coronary artery bypass graft surgery (CABG) or percutaneous coronary intervention (PCI). For patients with three-vessel CAD and SYNTAX scores ≥33 the five year data2 suggests MACCE rates that range from 27% for CABG versus 44% for PCI (p <0.001).

Figure 1

Figure 1

LAD = left anterior descending coronary artery; LCX – proximal left circumflex; RCA = right coronary artery.

The SYNTAX score was developed to prospectively characterize the coronary vasculature with respect to the number of lesions and their anatomical complexity, location and functional impact. Lower SYNTAX scores (less than 22) are indicative of less complex disease and are thought to represent less revascularization challenges and, therefore, may give rise to better prognosis. High SYNTAX scores may represent more complex lesion anatomy. These lesions provide greater technical challenges during PCI and, consequently, a higher risk of adverse events. CABG surgery bypasses the lesion and is less influenced by the complexity of lesions. Therefore, CABG may be more ideal for patients with high SYNTAX scores.

Given this information, it can be difficult deciding on the most optimal revascularization strategy for such diabetic patients with three-vessel CAD and low SYNTAX scores.

In the context of such risk stratification, which of the following statements is FALSE and should not be part of your patient evaluation?

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