Background Assessment of secondary event risk is now recommended for all coronary artery disease (CAD) patients. Many risk calculators have been developed for this purpose. However, their contribution to secondary prevention of CAD is limited because it is unknown whether high-risk patients would benefit more from intensive management. This study sought to apply a previously developed risk score of secondary event to predict readmission in CAD patients, and determine if higher-risk patients benefit more from intensive medical and interventional therapies.

Methods This State-wide longitudinal study included 19,940 patients admitted to a hospital in 2010 with CAD as the principal diagnosis. Patients were followed up till the end of 2015. A previously developed and validated risk score (PEGASUS-TIMI54) was used to estimate risks of future adverse events and stratify all patients into either low risk (score<6) or high risk (score≥6) as previously recommended. The primary outcome was all-cause readmission. Secondary outcomes included all-cause mortality and days alive and out of hospital within five years of hospital discharge. Cox proportional hazards regression and linear regression were used for analysis.

Results The high risk patients (n=6,573) had a significantly higher proportion of males and Indigenous people, had greater comorbidities, and were more likely to be readmitted or dead (all p<0.001) than their counterparts in the low risk group (n=13,367). Beta-blocker (hazards ratio HR=0.87 [95% CI: 0.79–0.95]), ACEi/ARB (HR=0.68 [95% CI: 0.62–0.73]) and PCI (HR=0.91 [95% CI: 0.88–0.95]) were negatively associated with readmission, and showed a negative interaction (p<0.001) with patients' predicted risks – implicating greater benefits for high-risk patients. CABG, on the contrary, was positively associated with readmission (HR=1.44 [95% CI: 1.15–1.80]) and showed a negative interaction (p<0.001) with patients' predicted risks. This finding suggests that patients receiving CABG were more likely to be readmitted than those not receiving CABG, but this trend reduced for patients with higher risks. Analysis of secondary outcomes suggest that all medical and interventional therapies reduced mortality risks, with the strongest effect size for CABG (HR=0.34 [95% CI: 0.29–0.48]). There was a negative interaction of statins, PCI and CABG with patients' predicted risks, implicating greater survival benefits for patients with higher risks.

Conclusions CAD patients can be effectively risk-stratified. The use of this information for a risk-guided strategy may maximize benefits for high-risk patients.