Sudden cardiac arrest is associated with sexual activity far more often in men than women, research suggests.But sex is a rare trigger for sudden cardiac arrest.Only 34 out of the 4,557 cardiac arrests examined occurred during or within one hour of sexual intercourse and 32 of those affected were men.Sumeet Chugh, of the Cedars-Sinai Heart Institute, said his study is the first to evaluate sexual activity as a potential trigger of cardiac arrest.The research was presented at a meeting of the American Heart Association.A cardiac arrest happens when the heart malfunctions and suddenly stops beating. It causes someone to fall unconscious and stop breathing and unless treated with CPR, it is fatal.This differs from a heart attack, where blood flow to the heart is blocked.It is known that sexual activity can trigger heart attacks, but the link with cardiac arrest was previously unknown.