A comprehensive and provocative new review addresses exercise and the heart (4). First, it covers the long-standing consensus that regular physical activity — even only 15 min of exercise a day — reduces the risk of cardiovascular disease (CVD). Then it covers athlete’s heart and recent research suggesting the paradox that lifelong extremes of endurance exercise may increase the risk of CVD. It argues that the transient decreases in cardiac function (“cardiac fatigue”) and mild increases in cardiac biomarkers of “acute myocardial injury” (troponins and natriuretic peptides) after endurance events are just physiologic changes. But then it broaches potential maladaptation to extremes of exercise, such as increases in coronary artery calcification, myocardial fibrosis, and atrial fibrillation in some studies of veteran endurance athletes. These studies have limitations, however, so this novel hypothesis — that a lifetime of extreme exercise can sometimes harm the heart — is still sketchy.
For this column, I start with a point made in this article: that at least 10% of heart attacks are tied to vigorous physical exertion. In other words, exertion can trigger heart attacks. Up to half of all heart attacks have likely triggers. The more we learn about triggers, the more we can help our patients avoid them. Below are some triggers to ponder.
As I covered in 2008, up to 15% of heart attacks occur during or soon after vigorous exercise, typically in sedentary men with coronary risk factors (3). In one study of heart attack survivors, in the first hour after heavy exertion, risk of heart attack rose more than 100-fold from baseline for habitually inactive persons, but for frequent exercisers, it rose less than three-fold (6). The largest studies on the cardiac risks and benefits of exercise are the Physicians’ Health Study and the Nurses’ Health Study. Both show that the risk of sudden cardiac death (SCD) during exertion is reduced by habitual exercise. In other words, exercise acutely increases, but ultimately decreases, the risk of SCD (4).
The pearl for patients and doctors alike is as follows: Exercise regularly. Stay fit. Never charge recklessly into a grueling new workout. Never take your heart by surprise.
Outbursts of Anger
A new study from Australia shows that temper tantrums tax the heart. Some 300 patients with acute heart attack and confirmed coronary occlusion by angiography rated their usual anger level and their level in the 48 h before the attack. Just over 2% reported blowing their stack within 2 h of the attack. The angry outbursts were provoked by arguments at home, in the community, or at work, or by road rage. Compared with their usual anger levels, the relative risk of heart attack from their fit of rage was 8.5. Mechanisms may include sympathetic activation that speeds the heart, raises blood pressure, constricts blood vessels, and activates clotting (1).
A new review of nine studies of rage and cardiovascular events — mainly heart attacks but also ischemic strokes or ventricular arrhythmias — concludes that, despite heterogeneity among studies, all nine found an increase in cardiovascular events in the 2 h after outbursts of anger (9). Extreme anxiety can be another emotional trigger of heart attack, and the same applies to sudden fright, as in the wake of earthquakes or missile attacks (1,3).
The pearl is as follows: Rage is your enemy. So temper your temper. Do not let Dr. Jekyll turn into Mr. Hyde. Count to 10. Consider stress reduction training, anger management, and avoidance of settings that can trigger your anger. Physicians may consider prescribing beta-adrenergic blockers or aspirin, both known to provide some protection against emotional triggers of heart attack (1).
A structured interview of nearly 800 heart attack survivors in Boston suggested that exposure to air pollution (fine particles) increased the risk of heart attack within 2 h and again the next day (10). This was soon followed by a pivotal report that tied acute heart attack to exposure to traffic. Nearly 700 heart attack survivors in a German city were asked about their activities on the 4 d before the attack. Researchers adjusted for exertion — as when bicycling — and for typical morning stress tied to heart attacks. They found that folks were three times more apt to experience a heart attack within an hour of driving, riding, or bicycling than during their activities away from traffic. They admitted that stress and noise could factor in, but they saw the effect even in the quieter, more relaxed bus or train rides. They concluded the most likely culprit was air pollution (11).
After two decades of research and debate, consensus holds that air pollution can trigger heart attacks, strokes, and irregular heart rhythms, particularly in people already at risk for these conditions. For heart attack (and stroke), very small particles that go down into the airways seem to be the main triggers. Extremes of hot or cold weather also may increase the risk of heart attack and/or compound the risk of air pollution. Pearls for prevention include the following: 1) Plan your activities for when and where air pollution is lowest. 2) If you exercise in high pollution, limit your outdoor time and take it easier; if you walk rather than jog, you will inhale less pollution. 3) Avoid exercising near busy roads (5).
Other Triggers Lurk
Other heart attack triggers abound; I have touched on some of them before. Heart attacks are more common in the morning and perhaps more common on Mondays, but what can you do about mornings and Mondays? In the 2 h after sexual intercourse, the risk of heart attack more than doubles, but for regular exercisers, the absolute risk of heart attack after sex is very low (3).
Beer binges can trigger heart attacks. So can smoking marijuana, it seems, notably by aging male baby boomers (8). Other likely triggers include cigarette smoking and heavy meals. Cocaine is a potent trigger: heart attack risk rises more than 20-fold soon after use (7). We know how to avoid these triggers.
A special hazard for sports fans is watching their favorite team lose (2). As you know, the word “fan” stems from “fanatic.” A more recent study of World Cup soccer found that the intense strain and excitement of viewing a dramatic soccer match — win or lose — more than doubles the risk of acute heart attack, particularly in men with known coronary heart disease (12).
In summary, we can identify a likely trigger in about 50% of all heart attacks. And we can pose practical pearls to prevent these pitfalls. We need more research to learn why the other 50% of heart attacks occur when they do. Onward and upward!
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