High Intensity Interval Training after Cardiac Resynchronization Therapy: a randomised controlled trial

Chronic heart failure (CHF) is an emerging problem in the Western World. In the
last decade, it has been shown that implantation of a biventricular
pacemaker/ICD, Cardiac Resynchronisation Therapy (CRT), can lead to a
substantial improvement in cardiac function, and, as a consequence, in a
reduction of morbidity and mortality in this patient category. In a
preliminary trial it was shown that the effects of CRT on exercise capacity and
quality of life can be improved even more by combining this therapy with
exercise training. However, the optimal training intensity has not yet been
established. In a recent trial in non-CRT heart failure patients, high
intensity interval training (HIT) was shown to be superior to moderate
intensity exercise training in terms of improving skeletal muscle metabolism,
as well as cardiac function. Because the mechanisms of improvement in cardiac
function by CRT and HIT are presumably different, we hypothesize that HIT after
CRT results in additive beneficial effects on exercise capacity through
improvements in skeletal muscle metabolism and perfusion, as well as through an
additional improvement in cardiac function (at rest and during exercise).

The main objective of the study is to investigate whether HIT after CRT results
in an additional increase in maximal exercise capacity. Secondary objectives
are to investigate whether HIT yields additional improvements in submaximal
exercise capacity, quality of life and left ventricular function. Another
objective is to investigate the physiological background of the additional
effects of HIT after CRT by measuring skeletal muscle tissue oxygenation (Near
Infrared Spectroscopy) and cardiac output during exercise (radial artery pulse
contour analysis method, LiDCO).

prospective randomised controlled intervention trial

HIT is performed 3 times a week during 12 weeks and consists of 4 intervals of
4 minutes cycling on a ergometer at 85-95% of the peak aerobic capacity (peak
Vo2) separated by 3 minute active pauses at 50-70% of peak Vo2. After each HIT
sessions patients will perform muscle resistance training at moderate
intensity. The entire program is supervised by trained physiotherapists

No adverse effects of exercise training performed by patients with a CRT device
have been seen reported. Yet, exercise training was shown to result in an
additional improvement in maximal exercise capacity, muscle strength and
quality of life. The HIT program that will be used in this study has not been
evaluated yet in patients that underwent CRT. However, it has been evaluated
extensively in other populations, like elderly patients, non-CRT CHF patients
and patients with coronary artery disease without any documented harmful
effects.
In order to reduce potential risks of exercise training, all patients perform a
maximal cardiopulmonary exercise test at baseline. Thresholds of the CRT device
for anti tachycardia pacing or defibrillation will be set substantially above
the maximal heart rate obtained at the maximal CPET. Training sessions will be
under supervision of trained physiotherapist in a clinical setting
Cardiac output during exercise is evaluated by using a method requiring radial
artery cannulation. This procedure is considered to be relatively safe with
complication rate of 0.09% for permanent ischemia of the hand. To ensure
collateral circulation a normal Allen test must be present. Cannulation will
be under local anaesthesia to minimize patients burden. In patients who take
oral anticoagulation , dosage will be temporarily adjusted(INR <1,5) for the
safety of the procedure