Silent heart attacks and the risks they pose

I recently had an ECG in preparation for a surgical procedure. The doctor said it showed I’d had a silent heart attack. How could I have had a heart attack and not known about it?

I know it sounds strange. After all, on television, heart attacks are portrayed in rather dramatic fashion. Typically, you see a person clutching their chest with agonizing pain. This mental image is embedded in our culture. But my colleague, Dr. Deepak Bhatt, a cardiologist at Harvard-affiliated Brigham and Women’s Hospital, cites a recent study that is the latest to show that heart attacks often can be “silent.”

Silent heart attacks are real. That is, the blood supply to a part of the heart has been shut down, and a part of the heart muscle dies as a result: That’s what a heart attack is.

However, in silent heart attacks, people often experience symptoms other than severe chest pain. Instead, they may have just a pressure or heavy feeling in the chest, or pain in the neck or jaw, or shoulder and arm. Or they may have shortness of breath, sweating, extreme fatigue, dizziness, or nausea. Whatever the symptoms, they may not attribute them to a heart problem. They may not even bring the symptoms to the attention of a doctor.

Or they may even have a heart attack that causes no symptoms.

The recent report from the Atherosclerosis Risk in Communities (ARIC) Study was a large one: Nearly 10,000 healthy people were followed for nearly a decade, on average. In nearly half (45 percent) of those who had a heart attack, the heart attack was “silent.”

If a heart attack didn’t cause any symptoms, and now is over, does it matter? For example, are you more likely to die from heart disease in the future? The research team compared three groups:

1. People hospitalized for heart attacks that caused symptoms.

2. People with silent heart attacks. 3. People without heart attacks. Not surprisingly, the risk of death in the first group was nearly five times as high as in the third group. Surprisingly and unfortunately, the risk of death in the silent heart attack group was three times as high as in the third group.

Older studies had more or less come up with similar findings. The present study extended these observations to a much more diverse population. The excess risk associated with silent heart attacks was found to be present in both men and women. And it was found in both white and African-American patients. Other races were not examined in this study.

So having a silent heart attack is a serious warning sign. It may not be quite as serious an omen as a heart attack that did cause symptoms. But it’s a lot more serious than never having had a heart attack. It means that it is much more important for you to observe a healthy lifestyle, and to treat any conditions (like high blood pressure or high cholesterol) that put your heart at risk.

Dr. Komaroff is a physician and professor at Harvard Medical School.)