Diseases can affect any part of the heart. However, the most common is the insidious disease of the coronary arteries called atherosclerosis. When this occurs, plaque, or fatty deposits, develops in the artery walls. Over a period of time, plaque can build up, harden and narrow the arteries, and restrict blood flow to the heart. It is this underlying coronary artery disease (CAD) that sets the stage for most heart attacks.

Clogging in one or more arteries precipitates an attack when the heart’s demand for oxygen exceeds the supply. Even in arteries less severely narrowed, a deposit of plaque can crack and lead to the formation of a blood clot (thrombus). Diseased arteries are also more susceptible to spasm. A blood clot can form at the site of a spasm, releasing a chemical that further constricts the artery wall, triggering an attack.

Of the majority who have symptoms of CAD, the Harvard Health Letter reports, about half will put off seeking immediate medical help. Why? “Usually because they don’t recognize what their symptoms signify or don’t take them seriously.”

John,a a heart-attack victim and one of Jehovah’s Witnesses, implores: “When you sense that something is not right, don’t delay in getting medical help out of fear of appearing melodramatic. I almost lost my life because I didn’t react quickly enough.”

What Happened

John explains: “A year and a half before my heart attack, I was warned by a doctor about my high cholesterol, a major risk factor in CAD. But I evaded the issue, as I felt that I was young—under 40—and in good health. I greatly regret that I did not take action then. I had other warning signals—shortness of breath with physical exertion, pains I thought were indigestion and, for several months before the attack, extreme fatigue. Most of these I blamed on too little sleep and too much job stress. Three days before my heart attack, I had what I thought was a muscle spasm in my chest. It was a minor attack prior to the big one three days later.”