Physicians have long struggled to identify and spot early warning signs that someone is at risk for, or about to go into, cardiac arrest. While there is no specific predictor for cardiac arrest, physicians take any symptoms and/or diagnoses of heart disease seriously and advise appropriate, immediate treatment.

In many cases, patients begin to experience symptoms days, weeks or even months before their arrest. This period is called the prodrome period. It may be marked by increased angina, dyspnea (breathlessness), palpitations, fatigue and other cardiac-related symptoms. However, these symptoms are not specific to cardiac arrest but can also signal an oncoming heart attack. Any heart patient, especially those with multiple risk factors, who experiences a change in their status and symptoms should immediately see a physician.

In the immediate period before a cardiac arrest occurs, the person's heart rate may increase and symptoms may intensify. In many people, however, there are no symptoms and the onset of the cardiac arrest is abrupt. Acute symptoms resemble those of a heart attack, including collapse and a lack of breathing. In a matter of minutes, the combination of a stopped heart and oxygen deprivation to the brain can cause sudden cardiac death. This explains why most sudden cardiac deaths occur before the patient receives emergency medical help or arrives at the hospital.

The risk for sudden cardiac death increases significantly in people with a family history of the condition. Because of this, researchers are developing tests to detect genetic markers that might place a person at higher risk of SCD. In addition, researchers may soon be able to test for a genetic predisposition to develop underlying conditions that might cause cardiac arrest and sudden cardiac death. Patients with a family medical history of sudden cardiac death or the conditions that could lead to cardiac arrest may wish to discuss the possibility of genetic testing with their physicians. However, genetic testing is expensive and may not be covered by traditional healthcare insurance.