The effects of HIIT on time to recurrence of atrial fibrillation after electro-cardioversion in patients with persistent atrial fibrillation: 

A randomized controlled pilot feasibility trial

Growing research demonstrates the favourable effects of high intensity interval training (HIIT) on cardiovascular outcomes. Reed et al. (2015) reported improvements in heart rate, blood pressure, aerobic and functional capacity and quality of life following a 10-week HIIT program in patients with permanent AF. The proposed mechanisms following chronic exercise training include improvements in diastolic function, left atrial volume index, vagal tone and cardiovascular risk factors.

A commonly used medical procedure performed in individuals with persistent AF to restore normal sinus rhythm is electro-cardioversion which sends electric shocks to the heart, thought to reset the rhythm back to its regular pattern. Unfortunately, rate of recurrence to AF following initial success is unacceptably high, as more than half of individuals report returning to AF within three to six months. Although pharmacotherapies, such as quinidine therapy, have been shown to lengthen time to recurrence, it is possible that lifestyle modification may be an alternative method to lengthen the time to recurrence, and additionally have a positive effect on cardiovascular disease (CVD) risk factors, such as decreasing body mass, waist circumference and fat mass, increasing functional capacity and fitness levels and improving quality of life. Pathak and colleagues (2015) found that each unit increase in cardiorespiratory fitness was associated with a 13% decline in risk of AF recurrence.

There is a need to examine the effects of exercise interventions, such as HIIT, which have the potential to improve long-term AF outcomes for those undergoing electro-cardioversion.