By Ralf Lehmann
Surgical or interventional coronary revascularisation is the primary therapeutic choice in coronary artery disease patients with multivessel disease or with involvement of the left main coronary artery (LMCA). The decision between revascularisation by percutaneous coronary intervention (PCI) and coronary artery bypass graft (CABG) in multivessel disease patients is often made by estimating the perioperative mortality for CABG using logistic regression-based clinical risk scores such as the EuroSCORE. However, the EuroSCORE is not validated regarding long-term outcome after CABG. The SYNTAX Score represents an anatomical risk stratification score for coronary artery disease patients and has recently been proposed to predict clinical outcome after multivessel PCI. However, the prognostic impact of different clinical and anatomical risk stratification scores for the long-term survival after multivessel PCI has not yet been investigated and compared sufficient. Finally, current guidelines on choosing a revascularisation strategy only focus on anatomical features rather than on clinical parameters.
In order to investigate these questions we conducted a single-centre registry with “all-comers” patients. Our study population consisted of 740 consecutive patients undergoing coronary stent implantation in at least two main vessel territories (LAD, RCA, RCX, RIM, LMCA=counted as two territories) in a single session at the University Hospital of Frankfurt, Germany. Clinical long-term follow-up regarding survival was available in a total of 726 (98%) patients with a mean follow-up of 5.3±2.1 years (patients alive).
Nearly half of the patients received multivessel PCI in the setting of an acute coronary syndrome (n=150 NSTEMI; n=191 STEMI). The mean age was 65±11 years, 77% were male, and 29% of the patients were diabetic. By definition the EuroSCORE was markedly lower for stable patients in comparison to patients with an acute coronary syndrome (stable 4.1±4.5, NSTEMI 13.9±13.3, STEMI 18.1±18.7, p <0.001). However, for the SYNTAX Score this difference was much less pronounced but still significant (stable coronary artery disease 14.9±8.6; NSTEMI 17.8±9.9; STEMI 18.3±9.0: p <0.001).
The patient population was divided into tertiles for each of the calculated scores.
Subsequently Kaplan-Meier survival estimates were performed to compare the different risk levels. Patients in the higher EuroSCORE tertile experienced a dramatically elevated mortality risk across the entire study period when compared with the lower two tertiles. The elevated mortality rate in the highest tertiles of the clinical scores was attributed in part to the high short-term mortality of patients with acute myocardial infarction and especially cardiogenic shock. This led us to perform a separate analysis for stable patients only, in which the discrimination of the long-term survival by tertiles of EuroSCORE was even more pronounced, as reflected by the diverging Kaplan-Meier curves. These results indicate that the discriminating potential of the clinical scores is not only powered by short term “acute” clinical parameters. Finally, the SYNTAX Score predicts long-term survival worse than EuroSCORE, as shown by a smaller difference between the highest and lowest tertiles. In the stable patient population, the SYNTAX Score lost its predictive ability completely.
The outstanding role of the EuroSCORE was confirmed by a multivariable Cox regression analysis adjusted for the relevant baseline characteristics. The EuroSCORE remained as independent predictors of long-term mortality in the entire population (HR per tertile 2.03; 95% CI 1.53–2.69).
In conclusion, a combination of clinical and anatomical risk factors may provide the optimal predictive model in patients undergoing multivessel PCI. Furthermore, the ideal combination of clinical and anatomic risk stratification should be conclusive for patients undergoing CABG as well.
Ralf Lehmann is an interventional cardiologist at Klinikum der JW Goethe Universität, Frankfurt, Germany.