Cardio Metabolic Health Congress – Official Blog

The Importance of Cardiac Stress Testing

Exercise stress tests demonstrate how the heart works during physical activity & stress. Because exercise makes the heart pump both harder and faster, exercise stress tests—or cardiac stress testing—can ultimately reveal problems with the heart’s blood flow. Designed to determine if one or more of the coronary arteries feeding the heart contain fatty deposits, or plaques, that block a blood vessel more than 70%, the tests can prove highly valuable for patients that exhibit specific risk factors and features. Stress tests can also detect any abnormal changes in heart rate or blood pressure, symptoms including shortness of breath or chest pain, and abnormal changes in the heart’s rhythm or electrical activity.

Dr. Deepak Bhatt, a professor of medicine at Harvard Medical School, chief of cardiology for the VA Boston Healthcare System, and CMHC faculty member, provides insight into what an exercise stress test can reveal about the heart: asserting that the procedure can play a critical role in diagnosing alarming symptoms like chest pain, particularly in populations with higher risk factors for heart disease. Dr. Bhatt states, “An exercise stress test is not 100% accurate—no medical test is…but it helps decide what the next step should be.”

How does a stress test work?

During a stress test, you walk on a treadmill or pedal on a stationary bicycle as an electrocardiogram (EKG) monitors the heart’s electrical rhythms through electrodes on the chest, legs, and arms; the electrodes have wires that record the electrical signals triggered by heartbeats. A cuff on the arm checks blood pressure during the test, and you are often asked to breathe into a tube to show how effectively you can breathe during exercise. As the test progresses, the exercise becomes more difficult—and you continue to exercise until your heart rate has reached a set target, or you develop symptoms that do not allow you to continue.

What information can doctors glean from a stress test?

Abnormal stress tests can point to a higher risk of coronary artery disease (CAD) for men with symptoms like chest pain during activity, or unexplained shortness of breath. Stress tests can become particularly worrisome for populations with higher risk factors including increased cholesterol, older age, and being overweight or obese. Yet Dr. Bhatt reinforces that a “normal” stress test cannot rule out the chance that a plaque will later rupture and block an artery, given that stress testing detects arteries that are severely narrowed: 70% or more, which is what causes initial symptoms. Heart attacks often occur from lesser blockages that ultimately rupture and form clots.

When should people consider stress tests?

The U.S. Preventive Services Task Force, an independent panel that makes general recommendations to physicians, counsels clinicians not to routinely offer exercise stress testing to patients without symptoms of strong risk factors for CAD, and physician groups including the American College of Cardiology support this guidance. Dr. Bhatt states that “the guidelines leave a lot to physician judgement, because we’re sometimes in a gray zone where we don’t really know what’s the ‘right’ thing to do for everyone.” Moreover, if you have recently been diagnosed with coronary heart disease (CHD) or experienced a heart attack, stress tests can indicate whether or not an exercise program would be harmful.


Updated Physical Activity Guidelines for Americans

Recently released by the U.S. Department of Health and Human Services, the second edition of the Physical Activity Guidelines for Americans offers recommendations for children and adolescents between 3 and 17 years of age: outlining the importance of regular exercise, and “moving more and sitting less.” Described as a critical resource for not only health professionals & practitioners but also policymakers, the guidelines serve as a supplementary resource in the ongoing effort to combat the high rates of chronic diseases—many of which are related to low rates of physical activity.

While the first edition of the guidelines was originally released a decade ago, and physical activity overall has generally improved since its release, the guidelines report that only 26% of men, 19% of women, and 20% of adolescents report sufficient amounts of physical activity. During a press conference, Brett P. Giroir, MD, assistant secretary for health for HHS emphasized the importance of the applications in the guidelines. “Inactivity causes 10% of premature mortality in the United States,” he stated. If only one quarter of inactive people could meet the guidelines and recommendations, approximately 25,000 deaths would be prevented in the country.

While physical activity can demonstrate immediate benefits including improvement in sleep hygiene, anxiety & blood pressure reduction, and improved insulin sensitivity—as shown in the report’s presentation of scientific evidence—the recommendations included in the guidelines reinforce more long-term benefits. Physical activity can improve cognition in children, mitigate the risk of postpartum depression, and help stave off dementia, Alzheimer’s disease, and excessive weight gain. Additionally, physical activity helps aid in the prevention of certain types of cancer.

The guidelines recommend specific amounts of exercise, including at least 60 minutes of ‘moderate-to-vigorous activity’ for children and adolescents between 6 and 17. Suggestions for adults recommend at least 150 to 300 minutes per week of moderate-intensity aerobic activity, coupled with muscle-strengthening activity 2 days per week. Moreover, the guidelines stress that adults should “move more and sit less,” since findings indicate that increased sedentary behavior has a strong correlation with cardiovascular disease, high blood pressure, and overall mortality. While the first guidelines recommended 10 minutes of physical activity per day, this edition states that Americans should simply move more frequently throughout the entire day, and that health benefits can be accrued from even small amounts of exercise.

In a related viewpoint published in JAMA, Giroir and Don Wright, MD, MPH from the HHS Office of Disease Prevention and Health Promotion write that these strategies could potentially yield “tangible increases in physical activity levels in the United States, and, as a result, reduce ever-increasing rates of chronic disease and burgeoning health care spending.” They further highlight the importance of physicians, health care professionals, and community & national leaders to take action in “this important call to Americans to make simple lifestyle changes that will improve longevity and quality of life.”

Nevertheless, given that an estimated 80% of adults do not currently meet the standards for sufficient physical activity, the guideline-recommended levels will remain a challenge, and require a comprehensive, coordinated approach from several sectors of society.

Pate RR. Department of Health and Human Services’ Physical Activity Guidelines for Americans. All presented at: American Heart Association Scientific Sessions; Nov. 10-12, 2018; Chicago.