Analysis of 6-minute walk test safety in pre-heart transplantation patients.
BACKGROUND
The 6-minute walk test (6WT) has been used as a means of assessment of the functional capacity, clinical staging and cardiovascular prognosis. Its safety and metabolic impact have not been frequently described in the literature, especially in patients with severe heart failure with clinical indication for cardiovascular transplantation.


OBJECTIVE
To evaluate the occurrence of arrhythmias and cardiovascular changes during 6WT. To correlate 6WT performance with clinical staging and cardiovascular prognosis.


METHODS
Twelve patients, 10 of whom males, aged 52 +/- 8 years were evaluated at baseline. 6WT was performed with telemetry electrocardiography, vital signs and lactate monitoring. The patients were followed-up for 12 months.


RESULTS
The patients walked 399.4+/-122.5 (D, m), reaching a perceived exertion (PE) of 14.3+/-1.5 and a 34% baseline heart rate variation. Two patients presented more severe pre-6WT arrhythmia which did not worsen with the exercise, four patients presented a significant increase of blood lactate levels (>5 mmol/dl), and three interrupted the test. The distance walked correlated with the ejection fraction (%) and functional class (NYHA). After 12-month follow-up, three patients died and seven were rehospitalized for cardiac decompensation. The D/PE ratio and 2-minute heart rate recovery (HRR2, bpm) were lower in the death group.


CONCLUSIONS
The clinical and electrocardiographic behaviors suggest that the method is safe, but it may be considered too strenuous for some patients with severe heart failure. Variables related to 6WT performance may be associated with the one-year follow-up mortality.
Cipriano
Gerson
G
Universidade de São Paulo, Universidade Federal de São Paulo, São Paulo, SP, Brazil. ciprianeft@uol.com.br
Yuri
Darlene
D
Bernardelli
Graziella França
GF
Mair
Vanessa
V
Buffolo
Enio
E
Branco
João Nelson Rodrigues
JN
D001145:Arrhythmias, Cardiac / Q000209:etiology*; D017558:Elective Surgical Procedures; D004812:Epidemiologic Methods; D005080:Exercise Test / Q000009:adverse effects*; D005260:Female; D006333:Heart Failure / Q000175:diagnosis / Q000401:mortality / Q000503:physiopathology*; D006339:Heart Rate / Q000502:physiology; D016027:Heart Transplantation; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D008875:Middle Aged; D013318:Stroke Volume / Q000502:physiology; D016138:Walking / Q000502:physiology*
D019344:Lactic Acid