Smoking. Smoking dramatically increases your risks of both heart attack and sudden cardiac death.

Can smoking cause sudden death?

First, nicotine is thought to have some immediate effects that can lead to life-threatening irregular heartbeats and sudden cardiac death. Second, cigarette smoke causes scarring of the heart tissue. This effect may persist long after quitting and contribute to the risk of sudden cardiac death.

What is the main cause of cardiac arrest?

Most cardiac arrests occur when a diseased heart's electrical system malfunctions. This malfunction causes an abnormal heart rhythm such as ventricular tachycardia or ventricular fibrillation. Some cardiac arrests are also caused by extreme slowing of the heart's rhythm (bradycardia).