The evolving characteristics and outcomes of acute myocardial infarction in Hong Kong, 1999–2018
Authors: Li H L , Tse Y K , Ren Q W , Wu M Z , Yu S Y , Yu S Y , Wong P F , Tse H F , Yiu K H 
Published: October 2021

Abstract

Background
The burden of myocardial infarction (MI) with its assorted comorbid complications is increasing parallel to rising life expectancy. Careful characterisation of patient characteristics and identification of short- and long-term complications is critical to their management. Nonetheless, data on the evolving profiles of patient features and outcomes, particularly in an Asian population, remain sparse.

Purpose
We aim to describe the evolving characteristics and outcomes of MI patients in Hong Kong in the past 2 decades.

Methods
From a well-validated territory-wide database in Hong Kong, we included patients with incident acute MI from 1999/01/01 to 2018/12/31. The primary outcome was 30-day all-cause death, while secondary outcomes include haemorrhagic stroke, and pneumonia, at both 30 days and 5 years. Temporal trends in baseline characteristics were evaluated using Poisson regression, while trends in outcomes were evaluated using Cox proportional hazard model, adjusted with demographics, comorbidities, and baseline medications.

Results
A total of 130,218 patients (age 73.6±13.9 years, 40.0% female) were included. Over time, while there was no change in the proportion of females (P=0.196), the increase in mean age (APC 0.23% [0.21 to 0.24], P&lt;0.001) was concordant with the increase in mean CCI (APC 5.1%, [4.8 to 5.3], P&lt;0.001), with more patients suffering from baseline comorbidities (Figure 1; range of APC 1.7% to 4.3%; all P&lt;0.001). The proportion of ST elevation increased significantly (APC 2.5% [2.4 to 2.5], P&lt;0.001).
The adjusted all-cause 30-day mortality rate decreased increased significantly (APC 0.3% [0.1 to 0.5], P=0.005). The increasing trend was significant in older patients (≥70 years), non-ST elevation, and female, while there was a decreasing trend mortality rate in ST elevation and young patients; no significant trend was observed in male. Strikingly, there is an alarming increase in the rate of haemorrhagic stroke (APC 3.4% [2.3 to 4.4], P&lt;0.001) and pneumonia (APC 1.5% [1.3 to 1.7], P&lt;0.001) at 30 days (Figure 2). Although the rate of 5-year all-cause death declined slightly (APC −0.8% [−0.9 to −0.6], P&lt;0.001), there were increasing rates of haemorrhagic stroke (APC 1.0% [0.3 to 1.7], P=0.004) and pneumonia (APC 3.8% [3.6 to 4.1], P&lt;0.001). Patients who were older, had ST elevation, and more comorbid were more likely to develop pneumonia.

Conclusions
Patients with MI have evolved to be older and more comorbid. Alarmingly, despite reduction in long-term all-cause death over time, the reduction was small; risk of death in short-term significantly increased and patients suffer from more complications including haemorrhagic stroke and pneumonia. These results highlight the emergence of extra-cardiac outcomes that drive poor prognosis and accentuate the need to develop tailored strategies to tackle these potentially lethal complications.

Funding Acknowledgement
Type of funding sources: Public Institution(s). Main funding source(s): The Shenzhen Key Medical Discipline; The Sanming Project of HKU-SZH Cardiology