Heart Rate Expenditure Correlates with Right Ventricular Function

Lachant, D.; Light, Albert; Mackin, Melissa Lehan; Schwartz, Ronald G.; White, R. James

doi:10.1513/annalsats.201909-683rl

Cited by 12 publications

(27 citation statements)

References 10 publications

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“…Figure 5C, 5D). Interestingly, for this group, HRE/d did not correlate with NT-pro BNP; this is different than our previous study (5) and was likely influenced by outliers with severe renal dysfunction or obesity. In PAH participants with paired walks, the changes in HRE/D correlated strongly with changes in REVEAL 2.0 and Emphasis 10 ( Figure 6).…”

Section: Heart Rate Changes During 6mwtcontrasting

confidence: 99%

“…Our findings strengthen our initial report (5) associated with greater variability which might reflect greater random variation (10). This was recently confirmed in 56 healthy young adults completing paired 6MWD (median 6MWD difference was 32.5 m +/-31.9 m) (4).…”

Section: Discussionsupporting

confidence: 89%

“…We also found that HRE/d did not correlate as strongly with age as 6MWD and may partially correct 6MWD for age. Our hypothesis that the HR changes associated with therapy intensification reflect improvement in RV function is supported by data (invasive, Fig 4, and in our previous nuclear study, (5)). In recently reported registries (21)(22)(23)(24), reassessment of risk after treatment intensification predicted long term outcomes better than baseline assessment (25).…”

Section: Discussionsupporting

confidence: 83%

“…A large number of our treatment intensification patients were treatment naïve with short walk distances at baseline so that absolute improvements in 6MWD were larger than generally observed for patients already on therapy. Only 11 patients underwent right heart catheterizations; the hemodynamic correlations are therefore preliminary but do confirm a small number of observations with different methodology in a previous cohort (5) relationship holds true with an exercising right ventricle. We did not have any patients on AV nodal blocking therapy, and patients on beta-blockers especially will need to be studied separately.…”

Section: Discussionsupporting

confidence: 56%

“…We hypothesized that the strategy would index walk distance for cardiac effort. We labeled this value 'HRE/d' for 'heart rate expenditure'/walk distance and found that HRE/d correlated strongly with resting RV function measured on same day nuclear (D-SPECT) imaging (5). Furthermore, HRE/d decreased after adding vasodilator therapy but was stable on different days for those not changing therapy.…”

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Heart rate monitoring improves clinical assessment during 6‐min walk

et al. 2020

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Right ventricular (RV) function is a predictor of outcomes in pulmonary arterial hypertension (PAH). The 6-minute walk test (6MWT) is likely an indirect measure of RV function during exercise, but changes in absolute walk distance can also be influenced by factors like effort and musculoskeletal disease. Paired 6MWT with continuous electrocardiogram monitoring were performed in stable PAH patients, patients adding PAH therapies, and healthy controls. Heart rate expenditure (HRE) was calculated (integrating pulse during 6MWT) and then divided by walk distance (HRE/d). We also evaluated changes in peak heart rate, time above age adjusted maximum predicted heart rate, and heart rate at 6 minutes. HRE/d was compared to invasive hemodynamic measures in patients who had right heart catheterization performed within seven days, WHO functional class assessment, and Emphasis 10 questionnaire. We measured two 6MWT in 15 stable PAH patients, 13 treatment intensification patients, and 8 healthy controls. HRE/d was reproducible in the stable PAH group (median difference, -0.79%), while it decreased (median difference, 23%, p =0.0001) after adding vasodilator therapy. In 11 patients with right heart catheterization, HRE/d correlated strongly with stroke volume, r=-0.72, p=0.01. Peak heart rate decreased after adding vasodilator therapy. HRE/d also correlated with WHO functional class and Emphasis 10 score. Continuous heart rate monitoring during 6MWT provides valuable physiologic data accounting for effort. HRE/d appears to enhance test reproducibility in stable patients while detecting change after adding therapy as compared to walk distance alone.

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Section: Heart Rate Changes During 6mwtcontrasting

confidence: 99%

Section: Discussionsupporting

confidence: 89%

Section: Discussionsupporting

confidence: 83%

Section: Discussionsupporting

confidence: 56%

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confidence: 99%

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Heart rate monitoring improves clinical assessment during 6‐min walk

et al. 2020

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Peak steps: Capacity for activity improves after adding approved therapy in pulmonary arterial hypertension

Lachant,

Light,

Lachant

et al. 2023

Pulm. circ.

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Pulmonary arterial hypertension (PAH) patients have low activity. Activity intensity or duration could be a measure of clinical status or improvement. We aimed to determine whether standard or novel actigraphy measures could detect increases in activity after adding therapy. This was a prospective, single‐center observational study evaluating activity after adding therapy in Group 1 PAH; we also report a validation cohort. For our study, two different accelerometers were used, a wrist (ActiGraph) and chest (MC10) device. Patients were analyzed in two groups, Treatment Intensification (TI, adding therapy) or Stable. Both groups had baseline monitoring periods of 7 days; the TI group had follow‐up at 3 months, while Stables had follow‐up within 4 weeks to assess stability. Activity time and steps were reported from both devices' proprietary algorithms. In ActiGraph only, steps in 1‐min intervals throughout the day were ranked (not necessarily contiguous). Average values for each week were calculated and compared using nonparametric testing. Thirty patients had paired data (11 Stable and 19 TI). There was no between‐group difference at baseline; we did not observe therapy‐associated changes on average daily steps or activity time/intensity. The top 5 min of steps (capacity) increased after adding therapy; there was no difference in the stable group. This key finding was validated in a previously reported randomized trial studying a behavioral intervention to increase exercise. Total daily activity metrics are influenced by both disease and non‐disease factors, making therapy‐associated change difficult to detect. Peak minute steps were a treatment‐responsive marker in both a pharmacologic and training intervention.

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Cardiac effort and 6‐min walk distance correlate with stroke volume measured by cardiac magnetic resonance imaging

Lachant,

Haight

et al. 2024

Pulm. circ.

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Right ventricular (RV) dysfunction in pulmonary arterial hypertension (PAH) is associated with poor outcomes. Cardiac magnetic resonance imaging (cMRI) is the gold standard for volumetric assessment, and few reports have correlated 6‐min walk distance (6MWD) and cMRI parameters in PAH. Cardiac Effort, (the number of heart beats used during 6‐min walk test)/(6MWD), incorporates physiologic changes into walk distance and has been associated with stroke volume (SV) measured by nuclear imaging and indirect Fick. Here, we aimed to interrogate the relationship of Cardiac Effort and 6MWD with SV measured by the gold standard, cMRI. This was a single‐center, observational, prospective study in Group 1 PAH patients. Subjects completed 6‐min walk with heart rate monitoring (Cardiac Effort) and cMRI within 24 h. cMRI was correlated to Cardiac Effort and 6MWD using Spearman Correlation Coefficient. Twenty‐five participants with a wide range of RV function completed both cMRI and Cardiac Effort. There was a strong correlation between left ventricle SV index and both Cardiac Effort (r = −0.70, p = 0.0001) and 6MWD (r = 0.67, p = 0.0002). Cardiac Effort and 6MWD were statistically separated in patients at prognostically significant thresholds of left ventricle SV index (>31 ml/m2), RV Ejection Fraction (>35%), and SV/End Systolic Volume ( > 0.53). Cardiac Effort and 6MWD are noninvasive ways to gain insight into those with impaired SV. 6MWD may correlate better with SV than previously thought and heart rate monitoring provides physiologic context to the walk distance obtained.

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Heart Rate Expenditure Correlates with Right Ventricular Function

Cited by 12 publications

References 10 publications

Heart rate monitoring improves clinical assessment during 6‐min walk

Heart rate monitoring improves clinical assessment during 6‐min walk

Peak steps: Capacity for activity improves after adding approved therapy in pulmonary arterial hypertension

Cardiac effort and 6‐min walk distance correlate with stroke volume measured by cardiac magnetic resonance imaging

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