Guideline-indicated treatments and diagnostics, GRACE risk score, and survival for non-ST elevation myocardial infarction

Abstract

Aims: To investigate whether improved survival from non-ST-elevation myocardial infarction (NSTEMI), according to GRACE risk score, was associated with guideline-indicated treatments and diagnostics, and persisted after hospital discharge.

Methods and results: National cohort study (n = 389 507 patients, n = 232 hospitals, MINAP registry), 2003-2013. The primary outcome was adjusted all-cause survival estimated using flexible parametric survival modelling with time-varying covariates. Optimal care was defined as the receipt of all eligible treatments and was inversely related to risk status (defined by the GRACE risk score): 25.6% in low, 18.6% in intermediate, and 11.5% in high-risk NSTEMI. At 30 days, the use of optimal care was associated with improved survival among high [adjusted hazard ratio (aHR) -0.66 95% confidence interval (CI) 0.53-0.86, difference in absolute mortality rate (AMR) per 100 patients (AMR/100-0.19 95% CI -0.29 to -0.08)], and intermediate (aHR = 0.74, 95% CI 0.62-0.92; AMR/100 = -0.15, 95% CI -0.23 to -0.08) risk NSTEMI. At the end of follow-up (8.4 years, median 2.3 years), the significant association between the use of all eligible guideline-indicated treatments and improved survival remained only for high-risk NSTEMI (aHR = 0.66, 95% CI 0.50-0.96; AMR/100 = -0.03, 95% CI -0.06 to -0.01). For low-risk NSTEMI, there was no association between the use of optimal care and improved survival at 30 days (aHR = 0.92, 95% CI 0.69-1.38) and at 8.4 years (aHR = 0.71, 95% CI 0.39-3.74).

Conclusion: Optimal use of guideline-indicated care for NSTEMI was associated with greater survival gains with increasing GRACE risk, but its use decreased with increasing GRACE risk.

Figure 1

Consort diagram of exclusions of the Myocardial Ischaemia National Audit Project (MINAP) dataset.

Figure 2

Adjusted* time-varying mortality rates by receipt of optimal care and clinical risk obtained from a flexible parametric model (odds scale, five degrees of freedom) with time varying covariates by GRACE risk score category for optimal care vs. suboptimal care across the full care pathway (A) and by the following subgroups of the care pathway: pharmacological therapies (B)^†, investigative and invasive coronary strategies (C)^‡, and lifestyle (D)^§,^. P = 0.004 for interaction. GRACE, Global registry of Acute Coronary Events, categorized into low (<109), intermediate (109 to ≤140), and high (>140) risk. *Model adjusted for demographic characteristics including sex, year, deprivation, previous acute myocardial infarction, previous angina, previous PCI, previous CABG, hypertension, peripheral vascular disease, chronic renal failure, chronic heart failure, cerebrovascular disease, diabetes mellitus, smoking status, and elevated cholesterol. ^†Including pre-hospital receipt of aspirin, aldosterone antagonist during admission, aspirin on discharge, P2Y₁₂ inhibition on discharge, ACE inhibitors (ACEi)/angiotensin receptor blockers (ARBs) on discharge, β-blocker on discharge, and HMG Co-A reductase inhibitor (statin) on discharge. ^‡Including receipt of a pre- or in-hospital electrocardiogram, echocardiography and coronary angiography. ^§Including referral for cardiac rehabilitation, smoking cessation advice and dietary advice.

Figure 3

Unadjusted landmark Kaplan–Meier survival curves and crude mortality rates by GRACE risk score category and receipt of optimal care vs. suboptimal care. This figure demonstrates the benchmarked crude mortality rates for the following time periods; 0–1 year, 1–2 years, 2–3 years, 3–8 years, across GRACE risk category by the receipt of optimal care. The percentages represent the crude mortality rates for each time period with the 95% confidence interval for each of the respective GRACE risk score categories. Population at risk at baseline; low GRACE risk category: 73 351, intermediate GRACE risk category: 59 201, high GRACE risk category: 52 005. Population at risk 3–8 years; low GRACE risk category: 70 069 intermediate GRACE risk category: 47 120, high GRACE risk category: 28 698.