Diagnosis

Diagnosis is the process of identifying a disease, condition, or injury based on a person’s symptoms, clinical history, physical examination, and the results of investigations such as blood tests, imaging, or monitoring. A diagnosis gives a name and framework to what is happening in the body, which guides treatment decisions and provides a basis for discussing prognosis.

In the context of cardiac arrest, the immediate priority after resuscitation is to identify the underlying cause. The most common cause is coronary artery disease leading to a heart attack, and this is typically investigated by urgent coronary angiography in the cardiac catheterisation laboratory. Where no coronary cause is found, further investigations look for inherited conditions such as hypertrophic cardiomyopathy, long QT syndrome, Brugada syndrome, or arrhythmogenic right ventricular cardiomyopathy.

Establishing a diagnosis after cardiac arrest matters for several reasons. It determines whether an implantable cardioverter defibrillator is needed, what medication is appropriate, whether family members should be screened, and how much physical activity is safe. In around 5 to 10% of cases, no cause is found despite thorough investigation; this is termed idiopathic ventricular fibrillation and can be psychologically difficult to accept.

Receiving a serious diagnosis can itself have psychological impact. Some people feel relief at having a name for what happened; others find uncertainty about the future distressing. Cardiac nurses, psychologists, and peer support networks can help survivors and families process a diagnosis and understand what it means for daily life.