Individuals with a greater exercise capacity have a reduced risk of developing atrial fibrillation (AFib), ischaemic stroke and major adverse cardiovascular events (MACE), according to the findings of a large study presented at the European Society of Cardiology (ESC) Congress, 2023.
AFib is the most common cardiac arrhythmia and has a number of different causes including auto-immune diseases such as rheumatoid arthritis.
Whether being physically fit might reduce the risk of developing AFib is unclear, although some evidence reveals a graded, inverse relationship between cardiorespiratory fitness and incident AFib, especially among obese individuals.
Exercise capacity and development of AFib
The study included 15,450 individuals without AFib who had a mean age of 54.9 years (59% male). All participants were referred for a treadmill test between 2003 and 2012.
Fitness was assessed using the Bruce protocol, where participants are asked to walk faster and at a steeper grade in successive three-minute stages. It was then calculated according to the rate of energy expenditure the participants achieved, which was expressed in metabolic equivalents (METs).
Participants were then divided into three fitness levels according to the METs achieved during the treadmill test: low (less than 8.57 METs), medium (8.57 to 10.72) and high (more than 10.72).
The researchers looked for independent associations between exercise capacity on the treadmill and the risk of new-onset AFib, risk of ischaemic stroke and MACE. The results were adjusted for potential confounders including age, sex, cholesterol level, kidney function, prior stroke, hypertension and any medications.
During the period of follow-up, new-onset AFib occurred in 3.33% of participants.
In fully adjusted models, each one MET increase in exercise treadmill testing, there was an associated 8% lower risk of AFib incidence (hazard ratio, HR = 0.92, 95% CI 0.88 – 0.97).
In addition, this one MET increase was also associated with a lower risk of ischaemic stroke (HR = 0.88, 95% CI 0.83 – 0.94) and a 14% reduced risk of MACE (HR = 0.86, 95% CI 0.84 – 0.88).
In fact, the probability of remaining free from AFib over a five-year period was calculated to be 97.1%, 98.4% and 98.4% in the low, medium and high exercise capacity groups, respectively.
Study author Dr Shih-Hsien Sung of the National Yang Ming Chiao Tung University in Taipei, Taiwan, said: ‘This was a large study with an objective measurement of fitness and more than 11 years of follow up. The findings indicate that keeping fit may help prevent atrial fibrillation and stroke.‘
