Assessing long-term temporal changes in myocardial infarction treatment and outcomes: chances and challenges

Over the last two decades, in most European countries the mortality rates of patients with acute myocardial infarction (MI) have been reduced.¹ This achievement is attributed to various factors, including earlier treatment initiation, improved coronary stents and revascularisation techniques, more refined dual antiplatelet therapy, and enhanced secondary prevention. Yet, improvement in clinical outcome may not be observed in all patients, as certain subgroups appear to be more vulnerable to inequity and disparity in cardiovascular healthcare. To confront this issue, The Lancet Regional Health—Europe recently published a series of manuscripts, evaluating current barriers faced by women, ethnic and racial minorities, elderly, and patients with mental health conditions.²

A large-scale retrospective study by Friis and colleagues, published in this issue of the journal, aligns with this series, complementing its perspective with novel and unique epidemiological data from Denmark on first-time MI in potentially vulnerable patient subgroups.³ The study gives an interesting overview of temporal trends from 2003 to 2022 in care and outcomes, assessing eight patient subgroups that were previously shown to be vulnerable. An overall reduction in mortality was observed among all patients over the 20-year period, with a more pronounced reduction in five-year mortality in the vulnerable patients. Yet, after 20 years, certain gaps persisted. Women, the elderly, the frail, those living alone, patients with a mental illness, and those with a low income showed higher mortality rates than their counterparts. Likewise, the initiation of guideline-directed treatment showed an overall increase for most patient groups, but vulnerable patients continued to experience a disadvantage by gaps in treatment initiation, suggesting persistent inequalities in healthcare.

The current study presents an extensive epidemiological view on temporal changes in first-time MI treatment initiation and mortality rates in several potentially vulnerable patient groups.³ This included comparisons between the last treated patients (2018–2022) and a historical dataset (2003–2008). Yet, assessing data over a 20-year period comes with several challenges that are not unique to this study, but are frequently overlooked. In fact, previous research that combined data of patients treated during long periods of time faced the same challenges.4, 5, 6

While the same inclusion and exclusion criteria and definitions of clinical outcomes were applied, several other conditions have changed over time. For instance, there have been alterations in the recommendations by the European Guidelines for both low-density lipoprotein targets and dual antiplatelet therapy duration and type, resulting in subtle differences in treatment between patients treated in different years. In addition, during the early phase of this study, use of drug-eluting stents was mostly reserved to patients who underwent percutaneous coronary intervention for indications other than ST-segment elevation MI (STEMI).⁷ Later on, international guidelines recommended all patients (including STEMI) to be treated with drug-eluting stents, of which the second-generation devices showed favourable safety profiles and improved clinical outcome.⁸

International consensus documents on the definition of MI have repeatedly been updated during the course of this study. A particularly important modification in diagnosing MI resulted from using high-sensitivity troponin assays, which allowed for an earlier identification of non-ST-segment elevation MI (NSTEMI). Moreover, its use reclassified a substantial proportion of patients with unstable angina as NSTEMI. The addition of more –often lower-risk– NSTEMI patients to the pool of all MI patients caused heterogeneity among the MI patients included over the past 20 years. It also reduced the overall MI mortality rate.⁹ In addition, as several vulnerable groups (e.g., women and elderly) tend to present more often with NSTEMI (than with STEMI),3, 4, 5 the observed reduction in MI mortality may be somewhat overestimated. In fact, it would have been interesting to analyse the temporal trends in STEMI patients only, as the composition of this MI subgroup is not affected by the issue of high-sensitivity troponin measurements, but the current retrospective study could not differentiate between STEMI and NSTEMI among their MI patients, identified from a national database using the 10th revision of the International Classification of Diseases (ICD-10 coding).

Nonetheless, the current study provides very interesting insights, and it reveals that both initiation of guideline-directed treatment and clinical outcomes after first-time MI have clearly improved over time. In addition, the 2018–2022 data show that gaps persist for several patient groups that are potentially vulnerable to inequity and disparity in cardiovascular healthcare. The findings highlight the relevance of this subject matter in the present day. More research assessing potential health disparities is required.^2,10 Further studies on the topic of the present study from countries outside Scandinavia are of interest, as the observations made in Denmark may not straightforwardly be generalized to all other parts of Europe.¹

Contributors

C. von Birgelen: literature search, conceptualization, writing–review & editing, supervision.

D. van Vliet: literature search, conceptualization, writing–original draft.

Declaration of interests

Both authors declared to have no personal conflict of interest, related to the content of this comment. They indicated an institutional research grant from Abbott Vascular to the hospital's cardiovascular research department.