Frailty is associated with adverse cardiovascular outcomes in type 2 myocardial infarction: a prospective registry study

Introduction Type 2 myocardial infarction is common, and patients with this diagnosis are often older and comorbid. Therefore, determining the optimal treatment strategy can be complex. Whether frailty is associated with cardiovascular outcomes and could inform management is uncertain. Purpose To determine if frailty influences cardiovascular outcomes in patients with type 2 myocardial infarction after adjusting for non-cardiovascular death as a competing risk. Methods The DEMAND-MI registry was a prospective multi-centre study identifying consecutive patients admitted to a secondary or tertiary care hospital with an elevated cardiac troponin concentration and an adjudicated diagnosis of type 2 myocardial infarction. Registry data were linked to health record data to determine baseline characteristics, management and clinical outcomes from recruitment to date of last follow up stratified by frailty status. Frailty was scored using the Rockwood Clinical Frailty Scale (CFS) and stratified into ‘fit’ (CFS 1-3), ‘mild’ frailty (CFS 4-5), ‘moderate’ frailty (CFS 6) and ‘severe’ frailty (CFS 7-9). The primary outcome was subsequent myocardial infarction or cardiovascular death. Subdistribution hazard ratios (sHR) were estimated using a Fine-Gray competing risk model accounting for non-cardiovascular death and adjusted for sex, recruitment status and mechanism of type 2 myocardial infarction. Results Between January 2018 and October 2020, 660 consecutive patients with type 2 MI were identified with 4,045 patient-years of follow-up (median 6.12 [5.54-6.69] years). In the cohort, 600 (91%) patients had documented clinical frailty scores: 211 (35%) classed as ‘fit’, 214 (36%) with ‘mild’ frailty, 113 (19%) with ‘moderate’ frailty, and 62 (10%) with ‘severe’ frailty. Higher clinical frailty scores were associated with longer length of hospital stay (P=0.001) and more co-morbidities (hypertension, cerebrovascular disease, atrial fibrillation, heart failure, and COPD; P<0.01 for all). Higher clinical frailty scores were associated with an increase in the risk of subsequent myocardial infarction or cardiovascular death (mild frailty; sHR, 1.48 [1.00-2.20]; P=0.049; moderate frailty; sHR, 1.98 [1.28-3.07]; P=0.002; severe frailty; sHR, 2.13 [1.25-3.63]; P=0.005) and non-cardiovascular death (mild frailty; sHR 2.52 [1.53-4.14]; P<0.001; moderate frailty; sHR, 2.97 [1.73-5.10]; P<0.001; severe frailty; sHR, 3.15 [1.70-5.82]; P<0.001) compared to ‘fit’ patients. Conclusion One-third of patients with type 2 myocardial infarction have moderate or severe frailty, which is an independent predictor of future cardiovascular and non-cardiovascular events. Incorporating frailty assessment into routine clinical evaluation may enhance risk stratification and support multidisciplinary decisions regarding investigation and treatment.