Effect of Heart Rate Reserve on Exercise Capacity in Patients Treated with a Continuous Left Ventricular Assist Device

Abstract

We hypothesized that an inadequate increase in heart rate (HR) during exercise was associated with low peak oxygen uptake (VO2 peak) seen in left ventricular assist device (LVAD) recipients and aimed to analyze the potential relation between HR and VO2 peak and use of drugs with negative chronotropic effect. Sixty-eight LVAD recipients (44 Heartmate 2 and 24 HeartWare Ventricular Assist Device) with support duration >1 month and a VO2 peak were included from two centers. Patients were 57 ± 13 years at time of VO2 peak and LVAD support duration was 483 ± 545 days. Peak oxygen uptake was 12 ± 4 ml/kg/min (40% ± 13% of predicted). Heart rate reserve (HRR = maximal HR − resting HR) was 59 ± 22 min− 1 (75% ± 15% of predicted for age, %HRR) and was significantly associated with VO2 peak (r = 0.244, p = 0.045). Predicted heart rate reserve was associated with %Predicted VO2 peak (P = 0.011). Chronotropic incompetence (CI) was observed in 44% and VO2 peak was clearly lower in patients with CI (10 ± 2.7 vs. 13 ± 4.6 ml/kg/min, p = 0.005). Beta-blockers (BB) were prescribed to 85% and adjusting for being on target BB-dose did not affect the correlation between %predicted VO2 peak and %HRR (r = 0.33, p = 0.024). In conclusion, almost half of LVAD recipients suffer from CI which is associated with lower VO2 peak. This relation did not seem to be affected by BB therapy.

Determinants of Functional Capacity and Quality of Life After Implantation of a Durable Left Ventricular Assist Device

“…Postimplantation mean pVO 2 values ( Figure 2B ) vary from 8.8 to 21.4 ml/kg/min (mean pVO 2 weighted for population size 13.2 ml/kg/min), showing that pVO 2 generally remains reduced after implantation at, on average, 48% of the expected value for age and sex. [ 12 – 16 , 21 – 23 , 25 – 29 , 31 – 37 , 39 – 42 , 44 – 47 , 61 – 63 ] A considerable proportion of the variance of postimplantation pVO 2 between published studies can be attributed to differences in the mean age of included patients. [ 11 ]…”

“…Several studies have documented the negative effects of chronotropic incompetence on exercise capacity in LVAD recipients. [ 12 , 21 , 27 , 38 , 46 ] Depending on the definition of chronotropic incompetence, it has been reported in approximately half of all examined LVAD recipients. Chronotropic incompetence may represent a somewhat clinically modifiable factor, because many LVAD recipients receive beta-blockers, digoxin or amiodarone and are equipped with pacing devices that could be programmed to improve chronotropic competence.…”

“…extra studies found by reference review or other sources) were included in this narrative review. [ 9 , 12 – 50 ]…”

A Guide to Physical Activity at Home During the Coronavirus Disease 2019 Pandemic

“…This is due to the close relationship between heart rate and oxygen consumption, especially when its intensity is between 50 and 90% of functional capacity (VO 2 max). Heart Rate Reserve (HRR) is the difference between a person's maximum Heart Rate (HRmax) (estimating as age -220) and resting Heart Rate (HRrest) [14]. The most accurate way to regulate the intensity of aerobic exercise using this method is to determine a specific heart rate with a VO 2 max or heart rate associated with lactate threshold.…”

Restoring pulsatility and peakVO2 in the era of continuous flow, fixed pump speed, left ventricular assist devices: ‘A hypothesis of pump's or patient's speed?’

“…21,25 The role of heart rate is under investigation, 26,27 since, although it seems not to affect LVAD flows, 25 a recent study investigating 68 LVAD recipients (44 HeartMate II and 24 HeartWare HVAD) reported chronotropic incompetence in 44% of the patients which was clearly associated with a lower peakVO 2 , while this relation was not affected by beta-blocker therapy. 28…”