Influence of practice patterns on outcome among countries enrolled in the SYNTAX trial: 5-year results between percutaneous coronary intervention and coronary artery bypass grafting

Objectives: To examine differences among participating countries in baseline characteristics, clinical practice, medication strategies and outcomes of patients randomized to coronary artery bypass grafting and percutaneous coronary intervention in the SYNTAX trial.

Methods: In SYNTAX, centres in 18 different countries enrolled 1800 patients, of which 8 countries enrolled ≥80 patients, what was projected to be a large enough sample size to be included in the analysis. Baseline characteristics, practice patterns and clinical outcomes were compared between the USA (n = 245), the UK (n = 267), Italy (n = 197), France (n = 208), Germany (n = 179), Netherlands (n = 148), Belgium (n = 91) and Hungary (n = 83). The remaining patients from other participating countries were pooled together (n = 382).

Results: Five-year results demonstrated significantly different outcomes between countries. After adjustment, percutaneous coronary intervention patients in France had lower rates of major adverse cardiac and cerebrovascular events [hazard ratio (HR) = 0.60, 95% confidence interval (CI) 0.37-0.98], while the incidence of repeat revascularization was higher in Hungary (HR = 1.89, 95% CI 1.14-3.42). Coronary artery bypass grafting showed the lowest rate of repeat revascularization in the UK (HR = 0.32, 95% CI 0.12-0.85). There were numerous differences in the risk profile of patients between participating countries, as well as marked differences in surgical practice across countries in the use of blood cardioplegia (range 3.1-89.0%; P < 0.001), bilateral internal mammary artery usage (range 7.8-68.2%; P < 0.001) and off-pump procedures (range 3.9-44.4%; P < 0.001). Variation was also found for percutaneous coronary intervention in the number of implanted stents (range 4.0 ± 2.3 to 6.1 ± 2.6; P < 0.001) as well as for the entire stents length (range 69.0 ± 45.1 to 124.1 ± 60.9; P < 0.001). Remarkable differences were observed in the prescription of post-coronary artery bypass grafting medication in terms of acetylsalicylic acid (range 79.6-95.0%; P = 0.004), thienopyridine (6.8-31.1%; P < 0.001) and statins (41.3-89.1%; P < 0.001).

Conclusions: Patient characteristics and clinical patterns are significantly different between countries, resulting in significantly different 5-year outcomes. This article presents specific data that can further improve outcomes in each country.

Clinical trials registry: NCT00114972.