The impact of frailty on the management and outcome of ST-elevation myocardial infarction in older patients
Authors: Bennett M , Batty J A 
Published: October 2021

Abstract

Background
Frailty is a clinical syndrome of increased vulnerability, resulting from age-associated decline in physiological reserve, compromising the ability to cope with acute stressors. Despite an increasing number of older, frail patients presenting with ST-elevation myocardial infarction (STEMI), there remains a paucity of guidance on how to approach the management of this complex group.

Purpose
To evaluate the impact of frailty on the management strategy and outcomes in older patients presenting with ST-elevation myocardial infarction.

Methods
A retrospective cohort study was performed, using linked patient records in The Nationwide Readmission Database. All patients aged ≥75 years that presented with STEMI (2015 – 2018) were included. International Classification of Disease (10th Edition; ICD-10) codes were used to ascertain exposures and outcomes. Frailty was quantified using the Hospital Frailty Risk Score (HFRS): an ICD-10-based scoring system that has been validated against established clinical frailty indices. Outcomes included: (i) management strategy (coronary angiography ± percutaneous coronary intervention, vs. conservative management), length of stay and 30-day mortality. Outcomes were modelled using multivariable binary logistic regression. Continuous variables are presented as: mean (standard deviation). Odds ratios (OR) are given with corresponding 95% confidence intervals (CI).

Results
From an overall dataset of 57,133,894 admissions, 368,201 patients presenting with STEMI were identified, of which 92,067 were aged ≥75 years. The mean age was 82.4 (5.1) years; 45,768 (49.7%) were female. The mean frailty score was 5.9 (SD 4.9, range 0 - 37.7). Patients were categorised by frailty status: low (HFRS &lt;5; n=46,336 [50.3%]), intermediate (HFRS 5 - 15; n=40,493 [44.0%]) and high risk (HFRS &gt;15; n=5,238 [5.7%]). Characteristics of the cohort are presented in Figure 1. Frail patients were less likely to undergo invasive management: 1,873 (35.5%) of the high risk group underwent coronary angiography vs. 36,888 (79.6%) of the low risk group; OR 0.14 (95% CI 0.13 - 0.15), P&lt;0.001. Length of stay in hospital increased proportionately with frailty: a 2-unit increase in HRFS was associated with one additional day in hospital (p&lt;0.001). 30-day mortality increased non-linearly with increasing HFRS and was markedly higher among patients at high risk for frailty, compared with those at low risk; OR 3.70 (95% CI 3.47 - 3.94; p&lt;0.001). The relationship between frailty score and outcomes is presented in Figure 2. Frailty remained the greatest single predictor of outcome following adjustment for other covariates, including age.

Conclusions
Frail patients presenting with STEMI are less likely to undergo invasive management and more likely to experience adverse outcomes. Quantification of frailty offers an opportunity to identify and address modifiable risk factors to improve post-STEMI outcomes in this vulnerable group.

Funding Acknowledgement
Type of funding sources: None.