Gilbert and Sullivan were correct to have Ko-Ko sing in "The Mikado" that "a little tomtit" died of a broken heart. There is a broken heart syndrome well-known to cardiologists, who also refer to it as stress cardiomyopathy or takotsubo cardiomyopathy. Sudden stress, usually of an emotional nature, can cause sudden cardiac death, angina, and acute congestive heart failure. I will first discuss the effects of acute stress on the heart, and then the far-reaching effects of chronic stress on the heart and the circulatory system.
The broken-heart syndrome, which usually affects women, is thought to be due to the effects of an acute surge of adrenalin on the heart. Such an acute surge can cause reversible spasm of the coronary arteries, ballooning of the left ventricle, and a stunning of the cardiac muscle syncytium. The precise mechanism is not known, but the effect is real, and has been observed many times. Cardiac enzyme tests for a heart attack are normal, but an echocardiogram will show a ballooning and dysfunction of a portion of the left ventricle, thereby causing acute heart failure. Coronary artery catheterization shows no sign of blockage, and the EKG changes are not those shown by a heart attack. Such an attack which can be manifested by acute chest pain and shortness of breath can look like an anxiety attack, but a cardiac exam will typically show signs of heart failure. In some cases, cardiac arrhythmias can also occur. Recovery with proper treatment tends to be rapid, typically within one week. The interval between the emotional shock (often caused by the death of a spouse) and the cardiac event is variable, and any severe emotional shock can be the trigger. There is even one (apocryphal?) story of a woman having such an attack after winning the lottery.
Chronic stress caused by anxiety or depression or problems at home or at work can also cause deleterious chemical changes in the bloodstream, with eventual effects on the circulation of coronary as well as peripheral arteries, and a possible fatiguing of the cardiac muscle. We know that the stress caused by these mental conditions can cause elevated adrenalin and cortisol levels, as well as an elevated pulse rate and white blood count. This effect also raises blood pressure and makes the blood more liable to clot. There is a concomitant elevation of fatty acids, cholesterol and triglycerides. Whether or not chronic stress can lead to heart disease is not known, but, as indicated, chronic stress elevates all the chemicals in our bloodstream that we would prefer to be lower to protect against cardiac disease.
Unfortunately, there is as yet little or no clinical data to show that lowering stress decreases the risk of developing a cardiac problem; even the type A hypothesis has not been well proven. And I doubt (but who knows?) that the effect of a daily glass of wine on lowering the risk of a heart attack is due to its relieving of stress. Since marijuana mellows most users, it will be interesting to examine the heart attack rates in Colorado and Washington State in 10 years, to see if there is any effect on the incidence of cardiac events that could be attributed to the chronic smoking of marijuana.