Using the 6-min Walk Test to Monitor Peak Oxygen Uptake Response to Cardiac Rehabilitation in Patients With Heart Failure

Prediction of peak oxygen consumption using cardiorespiratory parameters from warmup and submaximal stage of treadmill cardiopulmonary exercise test

This study investigates the quality of peak oxygen consumption (VO2peak) prediction based on cardiac and respiratory parameters calculated from warmup and submaximal stages of treadmill cardiopulmonary exercise test (CPET) using machine learning (ML) techniques and assesses the importance of respiratory parameters for the prediction outcome. The database consists of the following parameters: heart rate (HR), respiratory rate (RespRate), pulmonary ventilation (VE), oxygen consumption (VO2) and carbon dioxide production (VCO2) obtained from 369 treadmill CPETs. Combinations of features calculated based on the HR, VE and RespRate time-series from different stages of CPET were used to create 11 datasets for VO2peak prediction. Thirteen ML algorithms were employed, and model performances were evaluated using cross-validation with mean absolute percentage error (MAPE), R2 score, mean absolute error (MAE), and root mean squared error (RMSE) calculated after each iteration of the validation. The results demonstrated that incorporating respiratory-based features improves the prediction of VO2peak. The best results in terms of R2 score (0.47) and RMSE (5.78) were obtained for the dataset which included both cardiac- and respiratory-based features from CPET up to 85% of age-predicted HRmax, while the best results in terms of MAPE (10.5%) and MAE (4.63) were obtained for the dataset containing cardiorespiratory features from the last 30 seconds of warmup. The study showed the potential of using ML models based on cardiorespiratory features from submaximal tests for prediction of VO2peak and highlights the importance of the monitoring of respiratory signals, enabling to include respiratory parameters into the analysis. Presented approach offers a feasible alternative to direct VO2peak measurement, especially when specialized equipment is limited or unavailable.

SMART System in the Assessment of Exercise Tolerance in Adults

Health-oriented physical activity should meet two key criteria: safety and an optimal level of exercise. The system of monitoring and rationalization of training (SMART) was designed to meet them. SMART integrates a custom-configured inertial measurement unit (IMU) and a sensor with real-time heart rate measurement (HR) using a proprietary computer application. SMART was used to evaluate the safety and exercise load with 115 study participants: 51 women (44.35%) and 64 men (55.65%) aged 19 to 65 years. The exercise test was the 6MWT test. In 35% of the participants, the mean HR exceeded the recognized safe limit of HR 75% max. Ongoing monitoring of HR allows for optimal exercise and its safety. Step count data were collected from the SMART system. The average step length was calculated by dividing the distance by the number of steps. The aim of the present study was to assess the risk of excessive cardiovascular stress during the 6MWT test using the SMART system.

Factors Affecting Recovery of 6-Minute Walk Distance After Coronary Artery Bypass Grafting

Background: This single-center retrospective analysis investigated the number of days required for postoperative 6-minute walk distance (6MWD) to recover to preoperative values after coronary artery bypass grafting (CABG) and the factors influencing this recovery. Methods and Results: The 6MWD was measured in 101 patients (median age 69 years; 18 women) before and every day after CABG. Univariate and multivariate analyses were performed to identify factors affecting 6MWD recovery to preoperative values after CABG. The median number of days required for recovery of 6MWD after CABG was 9 (interquartile range 7-11 days). Patients were divided into 2 groups based on the median number of days required for recovery of 6MWD; there were 60 patients in the early recovery group (<9 days) and 41 in the "non-early" recovery group (38 who recovered after the median 9 days, and 3 who did not recover during hospitalization). Using univariate logistic regression analysis, diabetes (P=0.01), stroke (P=0.26), left ventricular ejection fraction (P=0.27), and grip strength (P=0.13) were selected for multivariate analysis. Multivariate logistic regression analysis revealed that diabetes (odds ratio 2.955; 95% confidence interval 1.208-7.229; P=0.02) was the only independent predictor of 6MWD recovery. Conclusions: Diabetes was the single factor influencing the recovery of postoperative 6MWD in patients undergoing CABG.

Influence of transitional care on the clinical manifestations among patients with COVID‑19: A single‑center, double‑blinded, randomized survey

Pneumonia and acute respiratory distress syndrome are the major complications of coronavirus disease 2019 (COVID-19). Transitional care is indispensable in successfully transitioning patients with COVID-19 from hospital to home and preventing adverse events of this disease. The purpose of the present study was to analyze the effects of transitional care on improvements in inflammation and pulmonary function in patients with COVID-19. Data of all hospitalized patients with COVID-19 (n=242) discharged from Mudanjiang Medical University (Mudanjiang, China) between May 2020 and October 2020 were retrospectively collected. Patients with COVID-19 had been hospitalized and assigned to receive transitional care (n=126) or usual care (n=116) and were followed up for 12 months. Hospital stay, inflammation and pulmonary function were compared in patients with COVID-19 between the transitional care and usual care group. Transitional care significantly improved physical symptoms, anxiety, depression and empathy of the patients for other patients affected. Compared to the usual care group, marked improvements in typical symptoms, including dyspnea, asthenia, cough, nausea, chest pain, myalgia, headache, fever, diarrhea, chest pain, dizziness, conjunctivitis, as well as disorders of smell and taste, were observed in the transitional care group. Patients in the transitional care group had a shorter hospital stay than those patients in the usual care group. Furthermore, transitional care decreased inflammation and ameliorated pulmonary function in patients with COVID-19. In conclusion, transitional care has an essential role in the improvement of physical symptoms, inflammation and pulmonary function in patients with COVID-19 [Chinese Clinical Trial Registry (ChiCTR) registration no. ChiCTR2200060295; 26.05.2022].

Use of 1-MNA to Improve Exercise Tolerance and Fatigue in Patients after COVID-19

COVID-19 is not only a short-term infection, as patients (pts) recovering from SARS-CoV-2 infection complain of persisting symptoms, which may lead to chronic fatigue syndrome. There is currently no evidence that nutritional supplements can assist in the recovery of pts with chronic fatigue syndrome. 1-Methylnicotinamide (1-MNA) is an endogenic substance that is produced in the liver when nicotinic acid is metabolized. 1-MNA demonstrates anti-inflammatory and anti-thrombotic properties. Therefore, we investigated whether 1-MNA supplements could improve exercise tolerance and decrease fatigue among patients recovering from SARS-CoV-2.

METHODS

The study population was composed of 50 pts who had recovered from symptomatic COVID-19. The selected pts were randomized into two groups: Gr 1 (NO-1-MNA)-without supplementation; Gr 2 (1-MNA) with 1-MNA supplementation. At the beginning of the study (Phase 0), in both groups, a 6-minute walk test (6MWT) was carried out and fatigue assessment was performed using the Fatigue Severity Scale (FSS). Both FSS and 6MWT were repeated after 1 month.

RESULTS

A significant improvement in the mean distance covered in the 6MWT was noted at follow-up in Gr 1-MNA, compared with Gr NO-1-MNA. We also noted that in Gr 1-MNA, the 6MWT distance was significantly higher after 1 month of supplementation with 1-MNA, compared with the beginning of the study (515.18 m in Phase 0 vs. 557.8 m in Phase 1; p = 0.000034). In Gr 1-MNA, significantly more pts improved their distance in the 6MWT (23 out of 25 pts, equal to 92%), by a mean of 47 m, compared with Gr NO-1-MNA (15 of 25 pts, equal to 60%) (p = 0.0061). After one month, significantly more patients in the group without 1-MNA had severe fatigue (FSS ≥ 4) compared with the group with supplementation (Gr 1-MNA = 5 pts (20%) vs. Gr NO-1-MNA = 14pts (56%); p = 0.008).

CONCLUSIONS

1-MNA supplementation significantly improved physical performance in a 6-min walk test and reduced the percentage of patients with severe fatigue after COVID-19. The comprehensive action of 1-MNA, including anti-inflammatory and anticoagulant effects, may be beneficial for the recovery of patients with persistent symptoms of fatigue and low tolerance to exercise after COVID-19.

Review of Recent Cardiac Rehabilitation Research Related to Enrollment/Adherence, Mental Health, and Other Populations

This review overviews three topic areas observed to be highly active in the cardiac rehabilitation (CR) research literature published in 2019 and 2020. Topics summarized were enrollment or adherence in CR programs; mental health, particularly depression, stress, and anxiety of patients participating in CR programs; and patients participating in CR programs with diagnoses other than coronary artery bypass graft, myocardial infarction, or percutaneous coronary interventions.