Prolonged heart rate recovery time after 6-minute walk test is an independent risk factor for cardiac events in heart failure: a prospective cohort study

OBJECTIVES: To determine whether the time for peak exercise heart rate to return to resting heart rate after the 6-minute walk test (6MWT) can predict cardiac events in patients with heart failure (HF) within 2 years. DESIGN: Prospective cohort study. SETTING: HF outpatient facility at a tertiary teaching hospital. PARTICIPANTS: Seventy-six patients with HF, New York Heart Association functional classification II and III, and left ventricular ejection fraction <50% MAIN OUTCOME MEASURES: Patients used a heart rate monitor to measure the time for peak exercise heart rate to return to resting heart rate after the 6MWT. Data were analysed using Polar Pro-Trainer 5 software (Kempele, Finland). Patients were followed for >2 years for cardiac events (hospitalisations and death). RESULTS: Thirty-four patients had cardiac events during the 2-year follow-up period. There was a significant difference in time to return to resting heart rate between the groups with and without cardiac events {with 3.6 [standard deviation (SD) A] vs without 2.8 (SD B) minutes; mean difference C; 95% confidence interval (CI) of the difference D to E; P=0.003}. No significant differences between patients with and without cardiac events were found for mean walking distance, mean heart rate recovery at 1 minute and mean heart rate recovery at 2 minutes. The receiver operating curve discriminated between patients with and without cardiac events (área under the curve 0.71, 95% CI 0.61 to 0.81; P< 0.001). Using logistic regression analysis, prolonged time to return to resting heart rate (≥3 minutes) independently increased the risk for cardiac events 6.9-fold (95% CI 2.34 to 20.12; P< 0.001). The Kaplan­Meier curve showed more cardiac events in patients with prolonged time to return to resting heart rate (P=0.028). CONCLUSIONS: Prolonged time to return to resting heart rate (≥3 minutes) after the 6MWT was an independent predictor of cardiac events in patients with HF.

Prolonged heart rate recovery time after 6-minute walk test is an independent risk factor for cardiac events in heart failure: A prospective cohort study.

OBJECTIVES: To determine whether the time for peak exercise heart rate to return to resting heart rate after the 6-minute walk test (6MWT) can predict cardiac events in patients with heart failure (HF) within 2 years. DESIGN: Prospective cohort study. SETTING: HF outpatient facility at a tertiary teaching hospital. PARTICIPANTS: Seventy-six patients with HF, New York Heart Association functional classification II and III, and left ventricular ejection fraction <50%. MAIN OUTCOME MEASURES: Patients used a heart rate monitor to measure the time for peak exercise heart rate to return to resting heart rate after the 6MWT. Data were analysed using Polar Pro-Trainer 5 software (Kempele, Finland). Patients were followed for >2 years for cardiac events (hospitalisations and death). RESULTS: Thirty-four patients had cardiac events during the 2-year follow-up period. However, there was a significant difference in the time to return to resting heart rate between the groups with and without cardiac events {with 3.6 (SD 1.1) vs without 2.8 (SD 1.1) minutes; mean difference of 0.79 (95% confidence interval (CI) of the difference 0.28 to 1.28; P=0.003}. No significant differences between patients with and without cardiac events were found for mean walking distance, mean heart rate recovery at 1minute and mean heart rate recovery at 2minutes. The receiver operating curve discriminated between patients with and without cardiac events (área under the curve 0.71, 95% CI 0.61 to 0.81; P<0.001). Using logistic regression analysis, prolonged time to return to resting heart rate (≥3minutes) independently increased the risk for cardiac events 6.9-fold (95% CI 2.34 to 20.12; P<0.001). The Kaplan-Meier curve showed more cardiac events in patients with prolonged time to return to resting heart rate (P=0.028). CONCLUSIONS: Prolonged time to return to resting heart rate (≥3minutes) after the 6MWT was an independent predictor of cardiac events in patients with HF.

Tempo de recuperação da frequência cardíaca como marcador prognóstico de eventos cardíacos / Heart rate recovery time as a prognostic marker of cardiac events

INTRODUÇÃO: O teste de caminhada de 6 minutos (TC6M) é um teste funcional amplamente utilizado em pacientes com insuficiência cardíaca crônica (IC). A distância percorrida no teste, bem como o delta de frequência cardíaca entre o repouso e a recuperação no 1° minuto (HRR1) e o delta de frequência cardíaca entre o repouso e a recuperação no 2° minuto (HRR2) têm sido propostos como marcadores prognósticos de eventos cardíacos em pacientes com IC. Nós hipotetizamos que a variação do tempo em minutos (denominado THRR) entre o pico da frequência cardíaca e o retorno à frequência cardíaca no repouso possa ser um marcador simples e de fácil obtenção no contexto clínico para estimar eventos cardíacos em pacientes com IC. OBJETIVOS: Nós investigamos se o THRR pode ser usado para estimar hospitalizações e morte ao longo de 2 anos de acompanhamento em pacientes com IC. MÉTODOS: Setenta e seis pacientes (média de idade 57 anos, NYHA II e III, IMC 25.5kg/m2, média FEVE de 33%) foram incluídos nesse estudo e divididos em Com eventos e Sem eventos. RESULTADOS: Trinta e quatro pacientes do grupo Com eventos e 42 pacientes do grupo Sem eventos tiveram, respectivamente as seguintes médias: THRR= 3.6 vs 2.8 min (p=0,003), distância percorrida= 463 vs 465 metros (p=0,930), HRR1=12 bpm para ambos grupos (p=0,952) e HRR2= 23 vs 22 bpm (p=0,723). A área sob a curva ROC para discriminar eventos e não eventos foi de 0,70 (IC95%: 0,58-0,82 e p=0,001). Usando a análise de regressão logística, o THRR ≥ 3 minutos dobrou o risco para eventos cardíacos (p=0,003). CONCLUSÃO: A variação de tempo entre o pico do exercício no TC6M e a recuperação da frequência cardíaca de repouso ≥ 3 minutos é um eficiente marcador clínico preditor de hospitalizações e morte em 2 anos para pacientes com IC. (AU)