Peek, N., Hindricks G., et al., on behalf of the PROFID consortium (2024). ‘Sudden cardiac death after myocardial infarction: individual participant data from pooled cohorts’, European Heart Journal. https://doi.org/10.1093/eurheartj/ehae326
Contributors
- Niels Peek
- Gerhard Hindricks
- Glen P. Martin
- Nikolaos Dagres
- See here for full list of authors – on behalf of the PROFID consortium
Why it matters
Sudden cardiac death is the leading cause of all deaths, claiming 20% of all lives. People who have previously suffered a myocardial infarction – commonly known as a heart attack – are at especially high risk of life-threatening ventricular arrhythmias, abnormal heartbeats that originate in the lower chambers of the heart. An implantable cardioverter-defibrillator (ICD) is a device put inside the chest to monitor and correct abnormal heart rhythms, which can be used to detect and halt dangerous arrhythmias. However, ICD implantation comes at significant healthcare costs and patient burden. It should be only be done in patients who really need it.
Clinical trials have previously found that ICD implantation boosts survival rates in patients with a poor left ventricular ejection fraction (LVEF), where the amount of blood leaving the heart each time it pumps is small. Current guidelines suggest fitting preventative ICD devices in these patients, but this approach is not always effective. Treatment advances have led to significant reductions in sudden cardiac death risk in patients with poor LVEF, meaning that most of the currently implanted ICDs are not needed. At the same time, many sudden cardiac deaths happen to patients with only mildly reduced or even normal LVEF, which raises the key question: Who is at risk of sudden cardiac death after myocardial infarction? This was what we aimed to find out.
As part of the EU-funded PROFID project, one of the largest of its kind, we looked at whether a combination of LVEF and additional predictors might identify the low-risk patients with poor LVEF who do not need ICD implantation, as well as identifying the high-risk patients with mildly reduced or normal LVEF who could benefit from it.
What we found
We analysed a pool of data that included 20 data sets from 140,204 post-myocardial infarction patients. The data included demographics, medical history, clinical characteristics, biomarkers, electrocardiography, echocardiography, and cardiac magnetic resonance imaging.
Patients were divided into three groups:
- People with ICDs for primary prevention and a LVEF of 35% or less
- People without ICDs and a LVEF of 35% or less
- People without ICDs and a LVEF of over 35%
We found that LVEF alone was a poor predictor of sudden cardiac death within each of these groups, and that consideration of a large number of other variables did not change that. Therefore, more accurate identification of low-risk patients with poor LVEF (who would thus not need ICD implantation) or of high-risk patients with normal LVEF (who would need it) was not feasible. These findings question the feasibility of approaches for personalized decision-making on ICD implantation. Our findings also confirmed that the risk of sudden cardiac death risk has substantially decreased, and is now also low in patients with poor LVEF. Routine defibrillator implantation may no longer be necessary in these patients: this policy needs to be re-evaluated.