Long-term non-cardiovascular morbidity risk remains elevated following myocardial infarction: a nationwide cohort study
Authors: Christensen D M , El-Chouli M , Strange J E , Nouhravesh N , Sindet-Pedersen C , Schjerning A , Schou M , Gislason G , Sehested T S G 
Published: October 2022

Introduction

Risk of cardiovascular events following myocardial infarction (MI) is high, and secondary preventive treatment is largely focused on reducing future cardiovascular risk. As gradual implementation of guideline-based treatments successfully leads to improved survival, long-term non-cardiovascular morbidity is likely of rising importance following MI.

Purpose

To determine the long-term risk of non-cardiovascular morbidity in a contemporary MI population with the aim of informing the need for and scope of prolonged surveillance.

Methods

We included all patients with a first-time MI in Denmark from 2001–2018 matched on age, sex, and date of discharge with up to 4 general population controls. We used the Aalen-Johansen estimator to estimate 1-year and 5-year risk of non-cardiovascular morbidity with death as a competing risk. Non-cardiovascular morbidity was defined as an in-patient hospital admission for any primary cause excluding cardiovascular diagnoses (International classification of diseases, 10th revision codes: I00–99). We also calculated 2-year and 6-year risks of non-cardiovascular morbidity in a stable population of post-MI patients and matched controls, i.e., participants alive with no hospital admissions for 1 full year following study entry. Finally, we estimated 1-year and 5-year risks of cause-specific non-cardiovascular morbidity.

Results

A total of 124,072 patients with MI who survived to hospital discharge were matched with 496,277 general population controls. Median age was 68 years and 35.5% were female. The 1-year and 5-year risk of non-cardiovascular morbidity was elevated for patients with MI compared to controls: 38.6% (95% confidence interval: 38.3–38.9) vs 15.3% (15.2–15.4) and 64.8% (64.6–65.1) vs 45.8% (45.7–45.9), respectively (Figure 1). Regarding cause-specific morbidity, risks of respiratory disease, gastrointestinal disease, and infectious disease particularly were high (Figure 2). For example, 1-year risk of infection was 4.5% for patients with MI and 1.8% for controls and 5-year risk of respiratory disease was 16.3% for patients with MI and 9.7% for controls. Furthermore, in the stable population (patients with MI, n=50,144; controls, n=159,467, median age 64 years, 33.0% female), risk of non-cardiovascular morbidity remained elevated at 2 years (17.2% [16.8–17.5] vs 11.3% [11.1–11.5]) and 6 years (49.2% [48.7–49.7] vs 39.8% [39.6–40.1]) post MI (Figure 1).

Conclusions

Risk of non-cardiovascular morbidity was high in patients following myocardial infarction, particularly for respiratory disease, gastrointestinal disease, and infectious disease. The risk remained elevated during long-term follow up. The study highlights the importance of additional focus on non-CV morbidity to further improve outcomes.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Danish Heart Foundation