Santa-Clara H; Abreu A; Melo X; Santos V; Cunha P; Oliveira M; Pinto R;
Carmo MM; Fernhall B.

European Journal of Applied Physiology. 119(8):1757-1767, 2019 Aug.
VI 1

AIMS: To determine the effects of high-intensity interval training (HIIT)
following cardiac resynchronization therapy (CRT) implantation in patients
with chronic heart failure (CHF), on noninvasive estimates of systolic
ventricular function, exercise performance, severity of symptoms and
quality of life.

METHODS: Cardiopulmonary exercise testing, resting transthoracic
echocardiogram and health-related quality of life assessment were obtained
before and at 6 months after CRT implantation in 37 patients with
moderate-to-severe CHF. Patients were randomized after CRT to either a
24-week HIIT group (90-95% peak heart rate, 2 days per week) or to a usual
care group (CON). Mixed design 2 x 2 repeated measures ANOVA were used to
test for differences within and in-between groups.

RESULTS: Improvements in health-related quality of life (HIIT = 98.54%,
CON = 123.47%), NYHA class (HIIT = 43.44%, CON = 38.30%) HR recovery at
minute 1 (HIIT = 32.32%, CON = 42.94%), pulse pressure at peak effort
(HIIT = 14.06%, CON = 9.52%, LVEF (HIIT = 42.17%, CON = 51.10%) and LV
Mass (HIIT = 13.26%, CON = 11.88%) were similar in both groups (p > 0.05).
Significant increases in CPET duration in the HIIT group (25.94%), and
increases in peak VO2 (HIIT = 8.64%, CON = 4.85%) and percent-predicted
VO2 (HIIT = 10.57%, CON = 4.26%) in both groups, were observed in the
intention-to-treat analysis.

CONCLUSION: Six months of HIIT in patients in CRT did not further
improved indices of functional capacity and health-related quality of
life, and LV structure and function, compared to CRT alone. However, HIIT
led to further improvements in exercise performance. It remains unclear
whether HIIT benefits patients in CRT to a similar degree as more
conventional forms of exercise training previously shown to maximize
benefits in CRT.