Pre-morbid frailty is associated with poor outcome after thrombolysis in older patients with ST-elevation Myocardial Infarction

Introduction: In recent years, the association of frailty has been established with a poor outcome after percutaneous intervention following an acute cardiovascular event. However, a larger proportion of the world population is unable to access the prohibitively expensive tertiary cardiac care and receives the more readily available, affordable and acceptable thrombolytic therapy in emergency situations. The current study was designed to explore the association of pre-morbid frailty with immediate and short-term outcome of thrombolysis in older subjects presenting with ST-elevation myocardial infarction to our hospital.

Methods: This was an observational prospective cohort study completed between 2015 and 2017 at a tertiary care teaching hospital in Delhi. Patients older than 60 years who presented to the hospital with ST-elevation myocardial infarction and underwent successful thrombolysis were included for the study. Complications such as bleeding, reperfusion reactions and allergic reactions were recorded whenever these were observed. In addition, complications such as re-infarction, stroke, cardiac arrest, cardiogenic shock and death were also recorded. In addition, a short-term outcome in terms of discharge, death, recovery was noted.

A pre-morbid frailty score was historically computed with inputs from the patients and their primary caretakers using a deficit count approach on a pre-defined list of fifty self-reported deficits.

The descriptive statistical analysis comprised of calculating means (standard deviations) and proportions (frequencies and percentages). The association of premorbid deficit score with thrombolysis success and other variables was tested by calculating mean ranks, and Mann Whitney U test was used as a statistical test of significance. Spearman correlation coefficient was used to determine the association between frailty and complications and morbidity and mortality indicators. Univariable logistic regression models were used to evaluate independent variables associated with outcome of thrombolysis to further explore the association between frailty and outcome. Independent variables found significantly associated with poor outcome were entered into a multivariable logistic regression model (forward) in addition to those considered scientifically relevant.

Results: In the present study, we found a significant association between a higher pre-morbid frailty status assessed by an interview-based deficit count score and poorer outcome of thrombolysis. Every unit increment in the frailty deficit count score on a scale of 50 points increased the odds of failed thrombolysis by 1.14 times. Frailty was also associated with an increased risk of reperfusion arrhythmias and cardiac arrest following thrombolysis. Additionally, we noted that higher the deficit score, lesser the resolution of ST segment on ECG, 90 minutes following thrombolysis.

Conclusions: Our study indicates that frailty determined by a premorbid count of health deficits is associated with the outcome of thrombolysis following myocardial infarction in older patients. The patients with greater count of deficits have a higher chance of failure. Our findings will help informed decision-making while managing older patients presenting with myocardial infarction and in-turn improve morbidity and mortality.