While most individuals are aware that chest pain can indicate the existence of heart disease, few are aware that shortness of breath also known as dyspnoea can be a dangerous cardiac symptom as well.
A team of Cedars-Sinai Medical Center researchers discovered that individuals with shortness of breath have a higher risk of dying from heart disease than those without symptoms, and even people with usual chest pain.
According to the findings of a study published in the New England Journal of Medicine, shortness of breath was a strong predictor of death from cardiac causes as well as death from any other cause.
The research was based on a retrospective review of roughly 18,000 people who were referred for cardiac stress testing and then followed up on subsequently. Researchers discovered that patients with shortness of breath were considerably more likely than patients without shortness of breath to die from cardiac causes. More than 1,000 of the patients denied having chest pain but said “yes” when asked whether they had shortness of breath.
“Patients often do not interpret shortness of breath as a serious symptom, but particularly in patients who have cardiac risk factors and in patients without lung disease, it may be the only sign of the presence of serious coronary artery disease that may need treatment,” explained Daniel Berman, sr. author of the study. “If we can identify patients with coronary disease before an event occurs, then the vast majority of the cardiac events could be prevented by modern therapies. The problem is identifying the patient at risk,” he said.
People without known coronary artery disease who had shortness of breath were four times more likely than asymptomatic patients to die from a cardiac cause, and twice as likely as patients who reported chest pain that was deemed typical cardiac pain, according to the retrospective analysis.
“These findings may in part be due to the fact that doctors are more likely to send patients with chest pain to bypass surgery or angioplasty than patients with shortness of breath,” added Berman.
Coronary artery disease is one of the leading causes of death in both men and women. It is caused by plaque build-up in the arteries surrounding the heart. Despite the fact that it is commonly associated with chest pain, approximately half of people with this deadly condition either die abruptly without prior symptoms or suffer a heart attack as the first symptom.
The study looked at the medical records of 17,991 people who were referred for stress testing by doctors who suspected or knew they had coronary artery disease based on their symptoms or risk factors.
Myocardial perfusion imaging, the most frequently utilized noninvasive method for detecting blocked coronary arteries, was used for stress testing. Patients exercise on a treadmill or, if they are unable to, are given medicine that dilates the heart’s arteries during the test.
Once the patient has reached “peak” stress, a small amount of radioactive imaging agent is administered, which concentrates in the heart based on blood flow, generating signals that are caught by a specific camera.
The cardiac images show the areas of the heart that don’t get adequate blood flow during stress and are particularly useful in estimating the likelihood of a cardiac event in the short term and determining whether angioplasty or surgery is necessary at that time.
In the United States, approximately 8 million stress myocardial perfusion scans were done.
The exact mechanism behind why people with shortness of breath but no chest discomfort were more likely to die was unknown. While some of the patients had underlying cardiac pumping problems that could explain their higher risk, the majority did not.
However, in patients who did not have a pumping function problem, the rate of cardiac events tripled in those who reported shortness of breath. Shortness of breath in the patients who were referred for testing could be due to ischemia, or a lack of blood supply to the heart muscle.
Shortness of breath, however, remained predictive of a negative outcome even after statistically correcting for the amount of ischemia. The scientists believed that the respiratory symptom could be caused by inflammatory proteins linked to the development of coronary artery disease—proteins that have previously been linked to malaise and fatigue.
When the authors employed statistical approaches to account for other significant differences between patient groups, shortness of breath remained an independent predictor of the chance of death from cardiac or any cause.
Thomas Marwick, M.D., of the University of Queensland, wrote an accompanying editorial: “Because the absence of chest pain has traditionally been interpreted to indicate a low likelihood of coronary disease—and indeed a low long-term risk—functional [stress] testing has been thought to contribute little to the evaluation of patients without angina [exertional chest pain]….These results should remind us that symptoms other than chest pain are of value in identifying patients with suspected coronary artery disease who should undergo functional testing.”
Marwick also mentioned that the myocardial perfusion test was efficient in identifying the degree of danger of cardiac death in patients with shortness of breath—the risk was more than five times higher in patients with highly abnormal scans than in patients with normal scans.
“Our findings are important for the public as well as for doctors,” added Berman. “Knowledge of these findings may lead doctors to refer patients with shortness of breath for testing, and then more readily send those who are found to be at serious risk for a life-saving revascularization procedure. For patients, increased awareness of the shortness of breath as a possible cardiac symptom will hopefully prompt those with unexplained shortness of breath to see their doctor sooner rather than later.”
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