By Dr Ananya Mandal, MD
Every year, around 450,000 Americans suffer a cardiac arrest. Of these, nearly 80% occur outside of the hospital setting, usually while the person is at home or at work. The death rate for these out-of-hospital cardiac arrests is at least 90% and of those who do survive, over half have permanent brain damage to some degree.
Among those who experience cardiac arrest while they are inside hospital, patient outcomes are improved due to the availability of defibrillation equipment and medical attention.
Factors affecting prognosis
There are several factors that influence the outcome or prognosis of a patient after a cardiac arrest.
Patient factors are those that are unique to the patient such as age, gender, lifestyle habits and co-morbidity. The chance of survival tends to be lower in older individuals, males and individuals who smoke, for example. The presence of other medical conditions such as blood infection, renal failure, metastatic cancer or stroke also have a negative impact on patient outcome.
Factors relating to the cardiac arrest itself are also associated with patient outcome. Examples include:
First monitored rhythm of the heart
If ventricular fibrillation or tachycardia is detected on the first electrocardiogram after the event, the chances of survival are 18% to 64%. For other rhythms, the chances of survival are much lower, ranging from 1.2% to 14%. VF/VT rhythms have a better outcome because they can be treated promptly and successfully with deﬁbrillation.
In addition, the fact that there is a VF or VT indicates that the arrest has begun recently because, if VF or VT is not treated immediately, the heart next becomes asystole and does not pump at all.
Patients with a shorter duration of cardiac arrest have a better prognosis and chance of survival than those with a longer duration of arrest. Shorter arrests are easily treatable and cause less damage to the tissues and vital organs.
The duration of cardiac arrest is usually much shorter when individuals live near to a hospital they can access, where medics can quickly intervene.
Reviewed by Sally Robertson, BSc
Last Updated: Nov 4, 2013