Atrial fibrillation and exercise

How a personalised exercise prescription can improve the health of AF patients.

Atrial fibrillation (AF) is a common type of heart arrhythmia that can affect people of all ages. Although the mechanisms are not completely understood, it involves dysfunction of the sinoatrial (SA) node, the electrical pacemaker of the heart. Simultaneously it may also involve erratic signalling patterns from pulmonary veins. These phenomena lead to disorganised and chaotic waves conducting intermittently through the atrioventricular (AV) node. This leads to irregular activation of the ventricles that generate the heartbeat. 

The primary pathologic change in AF is progressive fibrosis (and resultant weakening) of the atrial walls, due to atrial dilation. Fibrosis is not limited to the atrial walls and may occur in the SA and AV nodes. 

Ongoing medical management 

Upon presentation for an exercise assessment, the case report (see below) patient’s diagnostic classification was long-standing persistent AF. While the catheter ablation surgery in 2020 was initially successful in restoring sinus rhythm, he subsequently returned to asymptomatic AF after a period of nine months (initially notified by his Apple smart watch and subsequently confirmed by 12-lead ECG). He has been in AF since. He is taking 20mg of the direct oral anticoagulant rivaroxaban and 5mg of the beta blocker bisoprolol. Before any further interventions (such as a second ablation procedure) his cardiology team and GP have encouraged smoking cessation, a reduction in alcohol intake, and a supervised exercise programme to help with cardiorespiratory fitness and weight loss. The patient was referred directly and was not given an exercise stress test prior to commencement of his clinical exercise programme. 

Initial exercise assessment 

The patient was assessed for body composition using Tanita Bioelectrical Impedance scales. A sub maximal VO2 test (Chester step test) was performed to gauge cardiorespiratory fitness levels. In the case of a heart that is functioning in sinus rhythm, typically the presence of a beta blocker (such as bisoprolol) means an adjustment of 10-to-20 per cent reduction in calculations for target heart rates during exercise. However, in this case the beta blocker is part of a rate control strategy adopted by the patient’s cardiologist. Aligned to the long-standing persistent nature of this patient’s AF, reliance on heart rate readings to gauge exertion levels was not possible. Therefore, the sub maximal VO2 test (Chester step test) was performed using the Borg Rating of Perceived exertion (RPE Borg) scale to ascertain exertion levels. An additional six-minute walk test was also used to estimate VO2 max. 

	OCTOBER 2021 (INITIAL A X)	FEBRUARY 2022 (ON DISCHARGE)
WEIGHT (kg)	107.6kg	101.9kg
LEAN MUSCLE (kg)	67.9kg	68.2kg
BODY FAT (%)	32.9%	27.8%
CARDIORESPIRATORY FITNESS (VO2 MAX – ML/kg/MIN)	21 (poor)	32 (above average)
STRENGTH (kg)	RH – 37.1  LH – 38.5	RH – 41.0  LH – 40.6
6MWT (metres)	512	656

The upper limb strength levels were measured using hand-held dynamometry. Lower limb strength and ‘one rep max’ for a dead lift was measured using a ‘back and leg’ dynamometer. Some functional strength tests were also measured. SpO₂ levels were 99 per cent and pre exercise assessment blood pressure was 122/85. A musculoskeletal screening assessed for joint mobility and range of motion globally, noting reduced range bilaterally on cervical spine rotation, bilateral wrist flexion and extension, and left knee extension, secondary to mild osteoarthritis (OA) of this knee. 

How was the personalised exercise prescription designed for this AF patient 

There are currently no American College of Sports Medicine (ACSM) ‘FITT’ (Frequency, Intensity, Time, and Type) recommendations explicitly for AF. As such, the ACSM FITT guidelines for individuals with cardiovascular disease were applied. The exercise prescription in this case had four key component parts; aerobic, strength training, flexibility, and neuromotor (agility/co-ordination/balance). 

Aerobic – three-to-five days per week at an intensity of eight-to-12 on RPE Borg scale. The aerobic activity was not lower than 15-minute bouts in duration. Given the presence of OA in the left knee, aerobic work was encouraged through a mixture of cycling, swimming, and elliptical trainer initially to reduce weight-bearing load through the knee. A Polar H10 Heart strap, an Apple smart watch, and a familiarisation with the RPE Borg scale ensured effective and safe monitoring were all used to assist the patient when he was exercising alone. 

Strength training – a minimum of two sessions per week with 48-hours rest between sessions. Initially, the patient worked at 50-to-60 per cent of calculated one rep max, using eight major muscle groups. The patient did these sessions in the clinical setting supervised by a chartered physiotherapist. 

Flexibility – static stretches for all major muscle/tendon groups. These were performed approximately three times per week by the patient. 

Neuromotor – the patient had no identified balance issues on initial assess-ment. As such, the neuromotor aspect of the programme initially included single-leg strength training to improve function in the compromised left knee. After six weeks of dedicated strength training, increased weight-bearing through the left knee (and all weight-bearing joints) was performed using a series of ‘SAQ’ (speed, agility, quickness) drills using indoor ladders. This was goal-specific training as the patient wished to return to playing doubles tennis for the first time in nine years. 

Case report patient update 

After a 12-week personalised exercise prescription the patient made statistically-significant improvement in almost all areas measured. A key achievement was his weight loss of nearly 6kg, which will help improve his cardiovascular health, and has reduced weight-bearing load through his problematic knee. Knee pain was significantly reduced as per the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) index. Cardiorespiratory fitness had improved significantly, meaning the patient was now considered ‘above average’ as per age-related normative data. The patient has reduced alcohol intake per week and made some gradual changes to his diet. He is still smoking. As expected there is no change to his AF status, however, he is considerably fitter than previously. He is scheduled for an upcoming review with his cardiologist. If he can quit smoking he is hopeful he may be appropriate for a second ablation surgery in his bid to return to sinus rhythm. He is back playing doubles tennis and is looking forward to dancing at his daughter’s upcoming wedding. 

ANDREW DUNNE, Chartered Physiotherapist and Clinical Exercise Specialist, Personal Health Medical Exercise Clinic, Rathmines, Dublin, www.personalhealth.ie