Heart rate reserve predicts cardiovascular death among physically unfit but otherwise healthy middle-aged men: a 35-year follow-up study

Abstract

Low HRR was independently associated with increased risk of CV death in apparently healthy, middle-aged men. The predictive impact of HRR on CV death risk was, however, confined to unfit men.

Temporal Reduction in Chronotropic Index Predicts Risk of Cardiovascular Death Among Healthy Middle‐Aged Men: a 28‐Year Follow‐Up Study

“…We previously showed that HR reserve (the difference between maximal HR and resting HR) predicts cardiovascular death and showed that HR reserve and PF interact on cardiovascular risk prediction. After stratifying the same study population included in the present study by low, intermediate, or high PF, the predictive abilities of HR reserve were confined to the group of men with low physical fitness . We found no statistical interaction between chronotropic index or temporal change in chronotropic index and PF and hence, no stratification by PF level was validated.…”

“…Similar to HR reserve, the chronotropic index reflects the complex interaction between the autonomic nervous system and the cardiovascular system during exercise. We have discussed this relationship in more detail elsewhere …”

“…Such changes can, in the absence of relevant morbidity, influence the ability to reach maximal HR, lower resting HR, and modify classical cardiovascular risk factors such as blood pressure and cholesterol level . It is possible that use of temporal change in chronotropic index and other markers of autonomic imbalance could improve the accuracy of cardiovascular death risk prediction, for example, by reclassifying individuals for medium to low or high cardiovascular death risk …”

“…One established exercise‐derived cardiovascular predictor is the chronotropic index ([achieved maximal heart rate−resting heart rate]/[age‐predicted maximal heart rate−resting heart rate]), which is a standardized measure of heart rate (HR) change during exercise that reflects the combined effects of age, resting HR, and physical fitness (PF) . Measured HR increment during exercise, which is incorporated in the chronotropic index formula, is shown to be associated with cardiovascular death and its predictive ability is influenced by PF . Temporal changes in PF‐related or exercise‐derived parameters such as resting HR and exercise systolic blood pressure have been reported to predict cardiovascular disease and death .…”

“…6 Measured HR increment during exercise, which is incorporated in the chronotropic index formula, is shown to be associated with cardiovascular death [6][7][8] and its predictive ability is influenced by PF. 9 Temporal changes in PF-related or exercise-derived parameters such as resting HR and exercise systolic blood pressure have been reported to predict cardiovascular disease and death. 5,10 Despite inevitable individual changes in resting HR, maximal HR, and PF over time, [11][12][13] the prognostic impact of temporal change in chronotropic index on cardiovascular death risk has not been studied before.…”