Background: The heart school is an educational intervention offered in comprehensive cardiac rehabilitation (CR) in Sweden after suffering myocardial infarction (MI). The intervention aims to reduce modifiable risk factors and thereby also mortality and morbidity post-MI, yet has not been investigated with respect to hard endpoints.
Purpose: We estimated the association of attending the heart school with both all-cause and cardiovascular (CV) mortality, two and five years after admission.
Methods: This observational study identified patients with first-time MI as consecutively registered in the nationwide Swedish heart registry, SWEDEHEART (2006–2015), and were followed up using the Cause of Death registry for outcome events with minimal (<1%) loss to follow-up. Socioeconomic data was acquired from Statistics Sweden. The exposure was attending heart school as registered at first CR visit 6–10 weeks post-MI. Of 192059 MI admissions, 47316 unique patients with first-time MI who attended the first CR visit were identified as the study population (63.1 years, 24% females, 41% heart school attendees). Propensity score matching of treated patients with controls on 25 covariates was performed after multiple imputation. The association between heart school attendance and outcomes was estimated with Cox regression and survival curves in the matched sample. Several sensitivity analyses were conducted.
Results: In the matched sample, during the two and five year follow-up 493 and 1281 deaths by all-causes, of which 228 and 483 were cardiovascular deaths, occurred. The main analysis showed that attending heart school was associated with a lower risk of both all-cause (2-year HR = 0.53 [0.44, 0.64]; 5-year HR = 0.62 [0.55, 0.69]), and CV (0.50 [0.38, 0.65]; 0.57 [0.47, 0.69]) mortality. Results were similar in sensitivity analyses, including (a) landmark analysis conditioning on survivors 30, 60, 90, and 120 days post-MI, (b) after additional matching on other components of CR, and (c) in the male, female, <65 years, and 65–75 year old strata. See the figure for the stratified analysis with 5-year all-cause mortality.
Conclusion: Our results from this nationwide registry study indicate that attending heart school as part of CR, was associated with an almost halved all-cause and CV mortality in patients with first-time MI. These results warrant further investigation through adequately powered randomised trials.