Breathing problems: an underrated prodromal symptom of sudden cardiac death?

Breathing problems may more frequently precede cardiac arrest than chest pain. Further research can help emergency dispatchers distinguish between symptoms.

The researchers systematically evaluated pre-arrest calls and noted symptoms reported by the caller

According to a study from Denmark, breathing problems may more frequently precede cardiac arrest than chest pain. As this symptom is unspecific, further research is necessary to help emergency medical dispatchers distinguish between symptoms of a pre-arrest condition versus other medical issues.

Early identification of individuals at risk of out-of-hospital cardiac arrest remains challenging because little is known about the symptoms presented when contacting an emergency unit prior to an event. The study presented by Mr Filip Gnesin (Nordsjaellands Hospital, Denmark) intended to take a closer look at this important issue. 

Mr Gnesin and his team identified patients from the Danish Cardiac Arrest Registry who experienced an out-of-hospital cardiac arrest from 2016 through 2018 and had phoned the Copenhagen Emergency Medical Services up to 24 hours before their arrest. The researchers systematically evaluated these pre-arrest calls and noted symptoms reported by the caller, who could be the patient or a bystander. Finally, these patients were linked to nationwide databases to collect other data such as survival.

Of 4,071 patients with out-of-hospital cardiac arrest, 481 (11.8%) had pre-arrest calls. The median age of patients with pre-arrest calls was 74 years and 59.9% were men. The most commonly reported symptoms were breathing problems (59.4%), confusion (23.0%), unconsciousness (20.2%), chest pain (19.5%), and paleness (19.1%).

Findings indicate that breathing problems are an underrated warning sign of cardiac arrest

The most common occurring symptom pairs were breathing problems in combination with paleness (14.5%), confusion (14.1%), unconsciousness (13.5%), sweating (13.0%), and chest pain (11.9), respectively. An urgent medical response was dispatched in 68.7% of calls reporting breathing problems compared with 83.0% reporting chest pain. 

Mr Gnesin said: “More than 10% of patients experiencing an out-of-hospital cardiac arrest had a phone call to the emergency medical services up to 24 hours before their arrest either made by themselves or a bystander. Breathing difficulty was the most common complaint and much more common than chest pain. Despite this, compared to chest pain, patients with breathing issues were less likely to receive emergency medical help and more likely to die within 30 days after the arrest. These findings indicate that breathing problems are an underrated warning sign of cardiac arrest.”

Mr Gnesin concluded that creating awareness of breathing problems as a common early symptom of cardiac arrest may contribute, together with more research, to identifying more characteristics specific to cardiac arrest so that early intervention might be possible.

1. Gnesin F. Symptoms reported in calls to emergency medical services 24 hours prior to out-of-hospital cardiac arrest. Session: Coronary Artery Disease (Chronic)/Chronic Coronary Syndromes ePosters. ESC Congress 2021 – The Digital Experience, 27–30 August.
2. Gnesin F. Press conference ‘Preventing sudden cardiac death.’ ESC Congress 2021, 27–30 August.