Before the Heart Stops: The Overlooked Clues That Could Prevent Sudden Death in the Young

Sudden arrhythmic death syndrome (SADS) is a stealthy killer of young people, but new research has revealed potential warning signs that often go unrecognized.

By analyzing over 900 cases of sudden cardiac death in Sweden, scientists identified patterns like fainting spells, seizures, and abnormal heart rhythms that appeared before death. With better screening, especially among young athletes, many of these deaths might be preventable. The study also calls attention to the surprising link between psychiatric conditions, gastrointestinal symptoms, and sudden death risk.

Uncovering the Hidden Threat of SADS

Recognizing and detecting the signs that commonly precede sudden arrhythmic death syndrome (SADS) may help to prevent premature deaths, according to research presented today at ESC Preventive Cardiology 2025,^[1] a scientific congress of the European Society of Cardiology (ESC).

A Major Cause of Sudden Death in the Young

“SADS has not been well evaluated despite being one of the most common underlying causes of sudden cardiac death in young people, including young athletes,” said study author Dr. Matilda Frisk Torell of Sahlgrenska Academy – University of Gothenburg, Sweden. “We conducted an analysis of a large cohort of cases of sudden cardiac death in Sweden to describe the incidence of SADS and to characterize frequent findings that occurred before death to highlight opportunities for prevention.”

This was a retrospective observational study of the SUDden cardiac Death in the Young (SUDDY) cohort, which included all 903 cases of sudden cardiac deaths that occurred in young people aged 1–36 years in Sweden from 2000 to 2010.^[2] Five population-based controls were assigned per case. Information was analyzed from death certificates, autopsy reports, medical records, electrocardiograms (ECGs), any biological samples, and parental data.

Key Patterns and Warning Signs Identified

The researchers found that SADS accounted for 22% of all sudden cardiac deaths. Almost two-thirds of SADS cases (64%) were male and the median age of death was 23 years. Previous hospitalization or an outpatient care visit within 180 days of death was reported in 33% of SADS cases versus 24% of controls (p=0.038).

Among SADS cases, 4.2% had previously been hospitalized with a diagnosis of syncope versus 0.41% in the control group (p<0.001), while hospitalization due to a convulsion occurred in 3.5% of SADS cases versus 0.14% in controls (p<0.001). In total, 11% had previously known arrhythmic disease and 18% had a pathological ECG, with pre-excitation (premature activation of the ventricles) being the most common finding.

Around half (52%) of cases experienced symptoms before death, particularly palpitations, syncope, nausea/vomiting, and signs related to suffering from an infection. In total, 17% of cases had a previous psychiatric diagnosis and 11% had received psychotropic drugs.

Urgent Need for Screening and Awareness

Dr. Frisk Torell said: “With increased knowledge of the signs and symptoms that may precede SADS, such as syncope, seizure-like episodes, and pre-excitation, we may be able to identify young people at risk during healthcare visits. Our results also highlight the need for further study of psychiatric disease/treatment as risk factors for SADS and the potential for gastrointestinal symptoms and infectious diseases to act as triggers in predisposed individuals. Preparticipation screening of young athletes is an important opportunity to identify these signs and reduce the occurrence of SADS, and yet current levels of screening are low.”

Notes

1. ‘Sudden arrhythmic death syndrome (SADS) causing cardiac arrest in the young – risk factors are identifiable through preparticipation screening’ will be presented during Poster session (3) on 4 April at 09:00 to 13:45 CET in the Poster Area.
2. Stattin EL, Hagström E, Dahl N, et al. Cohort profile: the Swedish study of SUDden cardiac Death in the Young (SUDDY) 2000–2010: a complete nationwide cohort of SCDs. BMJ Open. 2022;12:e055557.

Meeting: ESC Preventive Cardiology 2025

Funding: This project was funded by grants from Marcus Borgström, The Swedish Society of Medicine, Norrbotten County Council, the Swedish Research Council 2020-01947, Uppsala University Hospital and Uppsala University, Sweden. Internal funding was received from the Region of Western Sweden (ALFGBG-720691).

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