Cognitive functions in severe congestive heart failure before and after an exercise training program

Abstract

Background: Congestive heart failure is associated with cognitive impairment, particularly of attentional skills. We assessed, in a hypothesis-generating study, the effect of an exercise training program on cognitive functions among patients with severe congestive heart failure.

Methods: Patients with severe congestive heart failure (n=20; New York Heart Association functional class III; left ventricular ejection fraction < or =35%) were evaluated before and following a standardized and supervised exercise training program (x2/week for 18 weeks; exercise group), while 5 additional patients did not undergo an exercise training program (control group). A battery of cognitive tests was used to assess cognitive functions. Physical performance was assessed by the 6-min walk test and the modified Bruce exercise test, cardiac index and systemic vascular resistance using thoracic electrical bioimpedance, and cerebral vasomotor reactivity to hypercapnia by means of the breath-holding index using transcranial Doppler.

Results: Time of completion of the trail making A (105+/-116 to 75+/-52; p=0.02) and B (169+/-100 to 119+/-65; p=0.002) tests, and of the Stroop part A (40+/-13 to 37+/-13; p=0.04) was shorter in patients completing the exercise training program, but not in control patients, while the other neuropsychological measures remained unchanged in both groups. Cerebral vasomotor reactivity to hypercapnia remained diminished (breath-holding index 0.64+/-0.27 vs. 0.68+/-0.37) despite significant improvements in exercise capacity (6-min walk test 308+/-87 to 423+/-91 m, p<0.001; modified Bruce exercise test 5.6+/-3.8 to 9.8+/-3.4 min, p<0.001).

Conclusions: Patients with severe congestive heart failure undergoing an exercise training program improve in some measures of cognitive functions that are limited to general attention and psychomotor speed. Based on these preliminary findings, further evaluations are designed within the framework of a larger controlled clinical trial.