We all suppose the stress is a trigger for heart disease but we always thought the kind of stress causing infarction was just suffered by aggressive executives and people living in the edge. A recent study shows how environmental stress makes the heart disease hypertrophic cardiomyopathy to appear in some people and the factors of that stress are so common as high blood pressure, diabetes and alcohol use. Not so glamorous but too deadly.
In hypertrophic cardiomyopathy, the heart muscle becomes abnormally thick, making it harder for the heart to pump blood. The disease can cause irregular heartbeats such as atrial fibrillation; obstructed blood flow that can cause shortness of breath, chest pain, dizziness and fainting spells; problems with the mitral valve; an enlarged ventricle (pumping chamber) that reduces the heart’s ability to pump blood; heart failure; and sudden cardiac death. It’s the leading cause of heart-related sudden death in people under age 30, including many athletes. For example, Boston Celtics basketball star Reggie Lewis died at age 27 after collapsing during a practice session.
More than 1,400 gene mutations have been linked to hypertrophic cardiomyopathy. An individual will have a 50 percent chance of inheriting the condition if one parent has the disease. About 1 in 500 people has hypertrophic cardiomyopathy, but the risk is much higher among people from India and other south Asian countries.
Dr. Sadayappan’s study involved mice that carried mutations that cause hypertrophic cardiomyopathy. To study the effect of environmental stress, researchers performed a procedure that mimics high blood pressure. This environmental stress significantly increased three measures of hypertrophic cardiomyopathy: The hearts became heavier, the pumping ability decreased and there were lower levels of a protein that is critical for the normal functioning of the heart. The protein is called cardiac myosin binding protein-C, or cMyBP-C.
The findings suggest that carriers of hypertrophic cardiomyopathy mutations who do not yet have symptoms may be at greater risk of developing cardiomyopathy from a variety of environmental stressors, such as high blood pressure, diabetes and alcohol use. This is due to the compounding effects of stress and insufficient levels of cMyBP-C, Dr. Sadayappan and colleagues wrote.
In an accompanying editorial, Jennifer Strande, MD, PhD of the Medical College of Wisconsin, wrote that the findings were unexpected. The findings lead to the “provocative suggestion” that stress plays a role in the disease process and may help explain why only some of the carriers of gene mutations get the disease.
“Stress may be a new modifier of the disease process and it is definitely worth another look,” Dr. Strande wrote. Dr. Strande earned her MD and PhD degrees from Loyola.