The Cooper Institute
 

Founded in 1970 by the "Father of Aerobics"
Kenneth H. Cooper MD, MPH

 
 
 

Preventing Atrial Fibrillation: Another Good Reason to Make Regular Physical Activity Part of Your Lifestyle!

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Tuesday, Sep 28, 2021

Atrial fibrillation (AFib) is the most common type of irregular heartbeat that is seen in clinical settings, and affects approximately 1% of the U.S. population. Risk factors for the development of AFib include older age, obesity, hypertension, diabetes, heart valve disease, and chronic inflammation. It has also become apparent in recent years that a low level of physical fitness is a risk factor for AFib. On the flip side, there is some evidence that excessive amounts of endurance training over many years may actually increase the risk of developing AFib.

Some individuals with AFib will not have any symptoms, while others will experience light-headedness, fatigue, heart palpitations, fatigue, and/or shortness of breath. If left untreated, AFib significantly increases the risk of stroke. In fact, it is estimated that about one in six strokes are due to AFib. It is important to note that many individuals with AFib do not have it constantly; their heart rhythm is actually normal some (or much) of the time. In other individuals, AFib is persistently present.

Let’s take a closer look at cardiovascular fitness and AFib. One recent study used a maximal treadmill stress test at baseline to measure the cardiovascular fitness of 5962 U.S. veterans who did not have AFib. Subjects were then divided into four categories of cardiovascular fitness, and followed for an average period of 8.3 years. During the follow-up period, 722 individuals developed AFib. The greatest risk for developing AFib was seen in the vets who scored in the least-fit category, while the lowest risk was seen in those who scored in the most-fit category. The authors concluded that moderate amounts of physical activity can help to improve fitness levels to the extent where there is a decreased risk of developing AFib.    

Another recent study utilized 308 overweight patients with AFib who were given a maximal treadmill stress test at baseline. A physician-led program that included behavior modification, weight loss, and exercise was then initiated. Upon completion of the program, a second maximal treadmill stress test was performed in order to measure changes in cardiovascular fitness. Frequency and duration of AFib episodes were tracked throughout the study, along with changes in body weight.

The patients were then divided into four groups based on their weight loss and changes in fitness that occurred during the study period:

Group 1: minimal weight loss (<10% loss of body weight) and minimal improvement in cardiovascular fitness

Group 2: minimal weight loss (<10% loss of body weight) and significant improvement in cardiovascular fitness

Group 3: significant weight loss (>10% loss of body weight) and minimal improvement in cardiovascular fitness

Group 4: significant weight loss (>10% loss of body weight) and significant improvement in cardiovascular fitness 

In Figure 1 below, the percentage of each group that experienced cessation of their AFib by the end of the study is shown; this is known as ‘AFib Freedom’.  

As you can see in the Figure, the least benefit was seen in Group 1 (minimal weight loss and minimal improvement in fitness), while the greatest benefit was seen in Group 4 (significant weight loss and significant improvement in fitness). This further adds to the to the notion that weight loss plus exercise is more effective than either by itself. Thus, for overweight and low fit patients with AFib, the best strategy to reach AFib Freedom is to combine significant loss of body weight with a significant improvement in cardiovascular fitness. Most overweight individuals can achieve both a moderate level of fitness and significant weight loss by following the current public health guidelines for physical activity in the overweight population (accumulate at least 300 minutes of moderate intensity aerobic activity per week). Please note that it may take several weeks or months to gradually build up to this level of activity if one is currently very sedentary. Like they say, Rome wasn’t built in a day! It actually took 2 days. Along with increased physical activity, a reduction of 300-500 calories consumed per day is clearly warranted for effective weight loss. Following the 2020-2025 Dietary Guidelines for Americans is a good strategy in this regard.  

 

References

Faselis, C., Kokkinos, P., Tsimploulis, A., Pittaras, A., Myers, J. Lavie, C….Moore, H. Exercise capacity and atrial fibrillation risk in veterans: a cohort study. (2016). Mayo Clinic Proceedings, 91(5):558-556.                                                                      dx.doi.org/10. 1016/j.mayocp.201603.002

Pathak, R., Elliott, A., Middeldorp, M., Meredith, M., Mehta, A., Mahajan, R….Sanders, P. Impact of CARDIOrespiratory FITness on arrhythmia recurrence in obese individuals with atrial fibrillation. (2015). Journal of the American College of Cardiology, 66(9), 985-995. dx.doi.org/10. 1016/j.jacc.2015.06.488