DEAR DOCTOR K:
My wife saw something on the news about a man who died of sudden cardiac arrest while jogging. Now she doesn’t want me to exercise. I’d really love to get my running shoes back on. What can I tell her to ease her worries?
I read your letter as I was cooling off after exercising. So your question is timely. Your wife’s concerns are understandable, but probably misguided.
I spoke to my colleague Dr. Aaron L. Baggish, the associate director of the Cardiovascular Performance Program at Harvard-affiliated Massachusetts General Hospital. He confirmed what I thought I knew.
Sudden cardiac arrest is caused by a lethal type of irregular heart rhythm called ventricular fibrillation. The lethal rhythm causes the heart to stop pumping blood — it just sort of quivers. If that rhythm is not immediately reversed — such as by a defibrillator machine — it results in death.
Sudden cardiac arrest can occur in a person with or without known heart disease. Probably the most common cause is atherosclerosis of the arteries of the heart that reduces the blood supply to some of the heart muscle.
The most important point to make is that regular, moderate-intensity exercise is actually the best way to prevent sudden cardiac arrest. There is solid scientific evidence that people who exercise regularly are less likely to develop cardiac arrest. Even people with heart disease who go through a carefully supervised exercise program are less likely to have a cardiac arrest.
Here’s what can be confusing: In all people, a cardiac arrest is more likely to occur when the heart is working hard than when it’s not. So, suppose you exercise for 30 minutes each day. That means you don’t exercise for the remaining 1,410 minutes in that day. Your risk of cardiac arrest per minute is greater while you exercise.
Nevertheless, a recent study found that exercise-related heart deaths are quite rare; they account for just 5 percent of sudden cardiac arrest cases. In the study, researchers reviewed 1,247 cases of sudden cardiac arrest in middle-aged men and women over a period of 11 years. Of these, only 63 cases occurred during exercise. Most occurred in men, and most of these men were jogging, playing basketball or cycling.
In the majority of cases, the cardiac arrest didn’t come out of nowhere. Two-thirds of the people who had cardiac arrest had known heart disease. And nearly one-third of them had experienced typical cardiovascular symptoms during the week before the sudden cardiac arrest, including chest pain and breathlessness.
This study offers two points of reassurance. First, exercise-related cardiac arrest is rare. The second important message is that heart disease often gives warning signs. Heed this message. If you feel any chest pain during exercise, have difficulty breathing, or even feel more drained than usual, stop and call a doctor for advice.
So if your doctor, who knows your medical condition, agrees, tell your wife that regular exercise will reduce your risk of sudden death during your remaining years together.