Heart Rate Expenditure Correlates with Right Ventricular Function

Advances in Clinical Care with Contemporary Cardiac SPECT

State of the art of cardiac SPECT imaging continues to advance. Contemporary clinical applications of cardiac SPECT are reviewed and illustrated. Beyond traditional stress and rest myocardial perfusion imaging, the role of digital SPECT technology, ultra low dose imaging with efficient stress first / stress only if normal imaging, deep learning algorithms relative to coronary angiography and SPECT CT, sourceless emission attenuation correction, myocardial blood flow and blood flow reserve to assess ischemic jeopardy, culprit ischemic territories, and cardiac allograft vasculopathy, advanced methods of SPECT detection of amyloid cardiomyopathy, resting MPI to define pre-operative regional scar prior to operative ablation, parametric radionuclide ventriculography to quantify dyssynchrony and benefit of biventricular pacing, assessment of treatment response of RV and LV function in patients with pulmonary hypertension, dual isotope MIBG imaging to assess cardiac risk, and the value proposition of real world effectiveness of SPECT cardiac imaging are illustrated.

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

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.

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

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.

EFFECTS OF ATHLETIC WALKING ON THE PHYSICAL ENDURANCE OF ATHLETES

ABSTRACT Introduction Athletic walking is a physical endurance test. This sport has a long competition time and a high load intensity. The long-term continuous movement of muscles is the most prominent characteristic of this sport. Strength and endurance are essential physical factors that determine the performance of the runners who do it. Physical endurance is an essential indicator to evaluate the level of physical training in athletic walking. Objective This study aims to analyze the effect of endurance training on the physical fitness and competition performance of athletic walkers. Methods This work selects four athletes as the research object. The athletes undergo one month of resistance training. The athletes recorded their physiological and biochemical indicators before and after resistance training. Then, the mathematical statistics method was used to analyze their physiological and biochemical indicators. Results Hemoglobin levels in the last three weeks of resistance training were significantly higher than in the first week (P<0.01). During endurance training, the athletes’ morning blood urea peak appeared in the first test after going to high altitude (P<0.05). Conclusion Endurance training can improve the fitness of athletic walkers. Resistance training effectively stimulates the blood system of athletes for at least two weeks. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

Cardiac Effort to Compare Clinic and Remote 6-Minute Walk Testing in Pulmonary Arterial Hypertension

BACKGROUND

The SARS-CoV-2 pandemic has limited objective physiologic assessments. A standardized remote alternative is not currently available. "Cardiac effort" (CE), that is, the total number of heart beats divided by the 6-min walk test (6MWT) distance (beats/m), has improved reproducibility in the 6MWT and correlated with right ventricular function in pulmonary arterial hypertension.

RESEARCH QUESTION

Can a chest-based accelerometer estimate 6MWT distance remotely? Is remote cardiac effort more reproducible than 6MWT distance when compared with clinic assessment?

STUDY DESIGN AND METHODS

This was a single-center, prospective observational study, with institutional review board approval, completed between October 2020 and April 2021. Group 1 subjects with pulmonary arterial hypertension, receiving stable therapy for > 90 days, completed four to six total 6MWTs during a 2-week period to assess reproducibility. The first and last 6MWTs were performed in the clinic; two to four remote 6MWTs were completed at each participant's discretion. Masks were not worn. BioStamp nPoint sensors (MC10) were worn on the chest to measure heart rate and accelerometry. Two blinded readers counted laps, using accelerometry data obtained on the clinic or user-defined course. Averages of clinic variables and remote variables were used for Wilcoxon matched-pairs signed rank tests, Bland-Altman plots, or Spearman correlation coefficients.

RESULTS

Estimated 6MWT distance, using the MC10, correlated strongly with directly measured 6MWT distance (r = 0.99; P < .0001; in 20 subjects). Remote 6MWT distances were shorter than clinic 6MWT distances: 405 m (330-464 m) vs 389 m (312-430 m) (P = .002). There was no difference between in-clinic and remote CE: 1.75 beats/m (1.48-2.20 beats/m) vs 1.86 beats/m (1.57-2.14 beats/m) (P = .14).

INTERPRETATION

Remote 6MWT was feasible on a user-defined course; 6MWT distance was shorter than clinic distance. CE calculated by chest heart rate and accelerometer-estimated distance provides a reproducible remote assessment of exercise tolerance, comparable to the clinic-measured value.

Comparison of chest- and wrist-based actigraphy in pulmonary arterial hypertension

Aims

Activity trackers for clinical trials and remote monitoring are appealing as they provide objective data outside of the clinic setting. Algorithms determine physical activity intensity and count steps. Multiple studies show physical inactivity in pulmonary arterial hypertension (PAH). There are no studies comparing different activity trackers worn on different parts of the body in PAH. We had patients with PAH simultaneously wear two different accelerometers, compared measures between the two devices, and correlated the measures with standard clinical metrics in PAH.

Methods and results

This was a single-centre, prospective observational study. Daily physical activity and daily total steps were measured using Actigraph GT9X Link and MC10 Biostamp nPoint for 5-10 days. Actigraph was worn on the non-dominant hand and the MC10 Biostamp nPoint was worn on the chest and leg with disposable adhesives. Twenty-two participants wore both accelerometers >12 h/day for an average 7.8 days. The average activity time measured by Actigraph was significantly higher than that measured by MC10 (251 ± 25 min vs. 113 ± 18 min, P = 0.0001). Actigraph's algorithm reported more time in light activity than moderate (190 ± 62 min vs. 60 ± 56 min, P = 0.0001). REVEAL 2.0 scores correlated highly with activity time measured using either device. Invasively measured haemodynamics within 7 days did not correlate with activity time or daily steps.

Conclusion

Different activity trackers yield discordant results in PAH patients. Further studies are needed in determining the best device, optimal wear time, and different thresholds for activities in chronic diseases.

Resting heart rate as a surrogate for improvement in intermediate risk pulmonary embolus patients?

BACKGROUND

Pulmonary embolism (PE) response teams (PERT) have been developed to improve in-hospital mortality. Identifying intermediate risk PE patients that will progress despite anticoagulation is difficult, especially because outcomes with modern anticoagulation are quite good.

OBJECTIVE

The primary aim of this study was to evaluate the rate of anticoagulation failure (new deep vein thrombosis or PE, right ventricular failure resulting in shock, cardiac arrest, or PE-attributable death) in intermediate risk PE patients managed by PERT. The secondary objective was to determine whether there was a significant decrease in heart rate 24 h after initiation of anticoagulation in intermediate risk PE.

METHODS

This was a retrospective observational study of patients treated for acute intermediate risk PE at the University of Rochester Medical Center who also had outpatient followup between November 2016-June 2019.

RESULTS

Ninety-two patients presented as intermediate-risk PE and had outpatient followup. Seventy-four patients were initially treated with anticoagulation. None of these patients failed anticoagulation. Of the eighteen intermediate risk patients that underwent advanced intervention, none failed anticoagulation first. There was significant decrease in resting heart rate 24 h after starting therapeutic anticoagulation, 107 beats/min vs 89 beats/min, p = 0.0001.

CONCLUSION

We did not observe anticoagulation failure in the management of acute, intermediate risk PE. Reductions in heart rate may reflect improvements in right ventricular function; we hypothesize that those whose heart rate does not fall may be optimal candidates for advanced intervention.

Diagnosis and Treatment of Right Heart Failure in Pulmonary Vascular Diseases: A National Heart, Lung, and Blood Institute Workshop

Right ventricular dysfunction is a hallmark of advanced pulmonary vascular, lung parenchymal, and left heart disease, yet the underlying mechanisms that govern (mal)adaptation remain incompletely characterized. Owing to the knowledge gaps in our understanding of the right ventricle (RV) in health and disease, the National Heart, Lung, and Blood Institute (NHLBI) commissioned a working group to identify current challenges in the field. These included a need to define and standardize normal RV structure and function in populations; access to RV tissue for research purposes and the development of complex experimental platforms that recapitulate the in vivo environment; and the advancement of imaging and invasive methodologies to study the RV within basic, translational, and clinical research programs. Specific recommendations were provided, including a call to incorporate precision medicine and innovations in prognosis, diagnosis, and novel RV therapeutics for patients with pulmonary vascular disease.

Inpatient Initiation of Oral Treprostinil in an Academic Medical System

PURPOSE

Clinicians may transition patients on parenteral or inhaled prostacyclins to oral treprostinil for ease of use or to avoid adverse effects related to parenteral therapy. However, few data are available to guide these transitions in inpatients. The purpose of this analysis is to describe the inpatient initiation of oral treprostinil at an academic medical system.

METHODS

This is a retrospective cohort analysis of patients newly initiated on oral treprostinil at Cleveland Clinic Heath System from 2015 to 2017. Demographic information regarding pulmonary arterial hypertension (PAH) history and previous PAH therapies were recorded. Outcomes evaluated included doses of oral treprostinil utilized, adverse effects related to therapy, and measures of clinical and functional status before and after the initiation of oral treprostinil.

RESULTS

Overall, 29 patients were prescribed oral treprostinil, of which 15 patients were included in the analysis. Common reasons for initiation of oral treprostinil included disease progression (6, 40%) and patient desire (4, 25%). The median duration of transition/initiation of oral treprostinil was 4 days (range, 3-11 days). Median daily dose of oral treprostinil on day 1 of initiation was 2 mg (0.25-4 mg). By day 7, median daily dose was 15 mg (0.75-27.75 mg). Common adverse effects related to therapy were gastrointestinal (7, 47%) and headache (4, 27%). No patients required discontinuation of oral treprostinil due to adverse effects within 90 days of initiation.

CONCLUSION

Inpatient initiation/transition to oral treprostinil was relatively well tolerated. Future studies should evaluate clinical outcomes surrounding the transitioning to oral treprostinil.

Heart rate monitoring improves clinical assessment during 6-min walk

Right ventricular (RV) function is a predictor of outcomes in pulmonary arterial hypertension (PAH). The 6-min 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 was 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 min. 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.