Exercise May Mediate Chronic Troponin Elevations, Obesity or Not

Marlene Busko

May 01, 2017

BALTIMORE, MD — Coming close to or meeting recommended levels of physical activity was associated with a smaller chance of having high levels of high-sensitivity cardiac troponin T (hs-cTnT)—a surrogate for myocardial damage—in a study of middle-aged and older people living in the community[1].

Being physically active was also linked with having a lower risk of heart failure, whether or not individuals were obese, in this analysis of data from the Atherosclerosis Risk in Communities (ARIC) study, which was published in the May 2017 issue of JACC: Heart Failure.

"We typically recommend physical activity as a means of losing weight or lowering blood pressure, but it seems . . . that if you are obese and you [engage in] physical activity, you have benefits irrespective of weight loss," lead author Dr Roberta Florido (Johns Hopkins University School of Medicine, Baltimore, MD) told heartwire from Medscape.

"If you really reach those guideline-recommended levels, that's when you have the most benefit, so it's important to aim for those 75 minutes a week of vigorous [physical activity] or 150 minutes a week of a combination of moderate and vigorous physical activity," she added.

The study also suggests that hs-cTnT could be used as a marker of cardiac health, according to Florido. "Maybe you could recommend physical activity for [patients] and monitor their troponin over time as a marker for this health behavior."

This study adds to close to 20,000 publications in the past decade that have investigated the link between exercise and heart disease, Drs Tariq Ahmad and Jeffrey M Testani (Yale University School of Medicine, New Haven, Connecticut) write in an accompanying editorial[2].

"Now we must get to the more difficult question: what are we going to do with this information?" they ask.

Degrees of Activity and hs-cTnT Levels

Being physically active is associated with a reduced risk of heart failure, especially in obese people, but it is not clear if physical activity might lessen chronic myocardial damage.

To investigate this, Florido and colleagues analyzed data from 9427 participants in ARIC who were 51 to 70 years old and free of cardiovascular disease in 1993–1995, when they replied to a questionnaire about physical activity. They also had hs-cTnT measured 3 years later.

The researchers converted activities into metabolic equivalents of task (METs), where 3 to 6 METs, "typically walking at a moderate pace, or some light biking, doing some gardening or some housework," was classed as moderate activity, and anything greater than 6 METs, such as "brisk walking up a hill, or biking for exercise and breaking into a sweat, or light jogging," was classed as vigorous activity, Florido explained.

Based on American Heart Association recommendations, participants were grouped into three categories of physical activity:

  • Recommended: >75 min/week of vigorous physical activity or >150 min/week of moderate or vigorous physical activity.

  • Intermediate: 1 to 74 min/week of vigorous physical activity or 1 to 149 min/week of moderate or vigorous physical activity.

  • Poor: No moderate or vigorous physical activity.

Only 43% of participants met the "recommended" level of physical activity (33% of obese participants and 47% of nonobese participants). The others had an "intermediate" (23%) or "poor" (34%) level of physical activity.

Compared with participants who met the recommended level of physical activity, those who did not were more likely to be women, African American, and current smokers, and they had higher systolic blood pressure, body-mass index, and prevalence of diabetes and lower HDL-cholesterol levels.

A total of 7.2% of participants had elevated hs-cTnT levels (>14 ng/mL).

Compared with people with a recommended level of physical activity, those with a poor level were more likely to have elevated hs-cTnT (odds ratio 1.31, 95% CI 1.08–1.59; P=0.001), after adjustment for age, race, sex, smoking, alcohol use, systolic blood pressure, antihypertensives, diabetes, cholesterol, HDL cholesterol, and triglycerides.

Over a median 15 years of follow-up, there were 1178 HF events. The adjusted rate of incident HF per 1000 person-years was lowest in nonobese patients who met the recommended level of activity (5.75) and highest in obese patients with a poor level of activity (14.09).

Further research is needed to elucidate the mechanisms underlying the association of physical activity and heart failure, Florido and colleagues write.

In the meantime, "given the strong association of hs-cTnT and heart failure, the current study supports promotion of physical activity as a key strategy for heart-failure prevention, particularly among high-risk subgroups such as people with obesity," they conclude.

"We Must Challenge the Status Quo"

Ahmad and Testani make an even stronger plea for cardiologists to work toward preventing cardiovascular disease.

"As a first step we must challenge the status quo," in which healthcare systems financially reward heart failure by reimbursements for performing complex procedures, they write.

"The prestige of cardiovascular divisions is gauged by their ability perform expensive diagnostic and therapeutic interventions with diminishing gains, rather than their impact on the heart health of the population they serve," they add. "Investigators are similarly rewarded on the basis of publications and grants, rather than their influence on healthy behavior."

On the other hand, Dr Paul Dudley White, a founding father of American cardiology, spoke widely to the general public about the benefits of physical activity and was instrumental in creating several bike paths, and Dr Valentin Fuster is following in his footsteps by setting up programs that teach children the importance of healthy habits.

Cardiologists should follow these examples and "strive to move beyond knowing [about behaviors that promote cardiovascular health] to actively preventing cardiovascular disease," Ahmad and Testani urge.

There is "a substantial amount of literature showing the benefits of exercise . . . not only cardiovascular [ones] but also . . . improvements in mood, depression, and cognitive function," Florido added.

"There are also some data that patients haven't heard from their physicians that they need to lose weight or . . . need to engage in physical activity or received some recommendation as to how much they should do.

"So part of it is us . . . telling our patients, 'Listen, this is what you need to do and this is why it's important,' and the other part is research on how to change behaviors and . . . get communities and their populations to engage in physical activity."

The study was supported by a Robert Wood Johnson Amos Medical Faculty Development Award, a National Institutes of Health (NIH)/National Heart, Lung, and Blood Institute grant, and an NIH/National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) grant. The authors and editorialists disclosed that they have no relevant financial relationships.

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