Is breathing frequency a potential means for monitoring exercise intensity in people with atrial fibrillation and coronary heart disease when heart rate is mitigated?

PURPOSE: Moderate-intensity aerobic exercise is safe and beneficial in atrial fibrillation (AF) and coronary heart disease (CHD). Irregular or rapid heart rates (HR) in AF and other heart conditions create a challenge to using HR to monitor exercise intensity. The purpose of this study was to assess the potential of breathing frequency (BF) to monitor exercise intensity in people with AF and CHD without AF. METHODS: This observational study included 30 AF participants (19 Male, 70.7 ± 8.7 yrs) and 67 non-AF CHD participants (38 Male, 56.9 ± 11.4 yrs). All performed an incremental maximal exercise test with pulmonary gas exchange. RESULTS: Peak aerobic power in AF ( V ˙ O2peak; 17.8 ± 5.0 ml.kg-1.min-1) was lower than in CHD (26.7 ml.kg-1.min-1) (p < .001). BF responses in AF and CHD were similar (BF peak: AF 34.6 ± 5.4 and CHD 36.5 ± 5.0 breaths.min-1; p = .106); at the 1st ventilatory threshold (BF@VT-1: AF 23.2 ± 4.6; CHD 22.4 ± 4.6 breaths.min-1; p = .240). % V ˙ O2peak at VT-1 were similar in AF and CHD (AF: 59%; CHD: 57%; p = .656). CONCLUSION: With the use of wearable technologies on the rise, that now include BF, this first study provides an encouraging potential for BF to be used in AF and CHD. As the supporting data are based on incremental ramp protocol results, further research is required to assess BF validity to manage exercise intensity during longer bouts of exercise.

Clinical outcomes of interval training in cardiovascular disease populations: A clinical perspective.

Nearly 20 years have elapsed since the first clinical trial investigated the impact of interval training on patients with cardiovascular disease (CVD). This clinical corner discusses the health outcomes of systematic reviews and meta-analyses and appropriately powered randomized controlled trials (RCTs) which have tested these interval training programs across various CVDs (i.e., coronary artery disease, heart failure, atrial fibrillation, peripheral arterial disease, and cardiac implantable electronic devices). The publications included in this clinical corner have shown that interval training leads to similar or superior improvements in V̇O2peak, functional capacity, pain free walking, QoL, anxiety, depression, and endothelial function, but the magnitude of improvements across varying protocols (e.g., length and number of work periods, intensities of work periods, duration of exercise sessions, frequency of exercise sessions, duration of program) and optimal dosage for males and females is unclear across CVD conditions. The heterogeneity in protocols, physical and mental health outcome measures, and lack of sex- and gender-based analyses calls for more high-quality research in this area.

Variability of cardiopulmonary exercise testing in patients with atrial fibrillation and determination of exercise responders to high-intensity interval training and moderate-to-vigorous intensity continuous training.

Disabling atrial fibrillation (AF)-related symptoms and different testing settings may influence day-to-day cardiopulmonary exercise testing (CPET) measurements, which can affect exercise prescription for high-intensity interval training (HIIT) and moderate-to-vigorous intensity continuous training (M-VICT) and their outcomes. This study examined the reliability of CPET in patients with AF and assessed the proportion of participants achieving minimal detectable changes (MDC) in peak oxygen consumption (V̇O2peak) following HIIT and M-VICT. Participants were randomized into HIIT or M-VICT after completing two baseline CPETs: one with cardiac stress technologists (CPETdiag) and the other with a research team of exercise specialists (CPETresearch). Additional CPET was completed following 12 weeks of twice-weekly training. Reliability of CPETdiag and CPETresearch was assessed by intraclass correlation coefficient (ICC) and dependent t-tests. The MDC score was calculated for V̇O2peak using a reliable change index. The proportion of participants achieving MDC was compared between HIIT and M-VICT using chi-square analysis. Eighteen participants (69±7 years, 33% females) completed two baseline CPETs. ICC was significant for all measured variables. However, peak power output (POpeak: 124±40 vs. 148±40 watts, p<0.001) and HR (HRpeak: 136±22 vs. 148±30 bpm, p=0.023) were significantly greater in CPETresearch than CPETdiag. Few participants achieved MDC in V̇O2peak (5.6 mL/kg/min) with no difference between HIIT (0%) and M-VICT (10.0%, p=0.244). POpeak and HRpeak differed significantly in patients with AF when CPETs were repeated under different settings. Caution must be practiced when prescribing exercise intensity based on these measures as under-prescription may increase the number of exercise non-responders.

Screening for sarcopenia with SARC-F in older patients hospitalized with cardiovascular disease.

OBJECTIVES: SARC-F ≥ 4 points are used for detecting sarcopenia; however, finding a lower SARC-F cut-off value may lead to early detection of sarcopenia. We investigated the SARC-F score with the highest sensitivity and specificity value to identify sarcopenia in older patients with cardiovascular disease (CVD). Motor performances were also examined for each SARC-F score. METHODS: This retrospective cross-sectional study examined the sensitivity and specificity of every 1-point increase in SARC-F score to predict sarcopenia. Eligible participants included patients with CVD (≥ 65 years old) who were admitted for acute CVD treatment and participated in cardiac rehabilitation. Patients completed the SARC-F questionnaire and the sarcopenia assessment. Areas under the curves (AUCs) were investigated for the ability to predict sarcopenia. Multivariable linear regression was used to compare the mean value of physical functions (e.g., Walking speed, leg strength, and 6-minute walking distance) of each SARC-F score. RESULTS: A total of 1066 participants (63.8% male; median age: 78 years) were included. Sarcopenia was present in 401 patients. SARC-F cut-off ≥ 2 presented the optimal balance between sensitivity (68.3%) and specificity (55.6%) to detect sarcopenia (the AUCs = 0.658; 95% confidence interval: 0.625-0.691). Even when the patients have low scores (1-3), increasing every 1 point of SARC-F score was associated with lower physical functions, such as lower muscle strength and shorter walking distance (all p < 0.001). CONCLUSIONS: SARC-F cut-off ≥ 2 was optimal for screening sarcopenia, and even a low SARC-F score is helpful in finding earlier sarcopenia and low physical function in patients with CVD.

Effect of change in hepato-renal function and cardiac rehabilitation on mortality in patients with heart failure.

BACKGROUND: Patients with heart failure (HF) often suffer from hepato-renal dysfunction. The associations between hepato-renal function changes and mortality remain unclear. Further, the effect of cardiac rehabilitation (CR) on mortality and motor functions in patients with HF and hepato-renal dysfunction requires investigation. METHODS: We reviewed 2522 patients with HF (63.2 % male; median age: 74 years). The association between changes in hepato-renal function assessed by the Model for End-stage Liver Disease eXcluding INR (MELD-XI) score and mortality was examined. The association of CR participation with mortality and physical functions was investigated in patients with HF with decreased, unchanged, and increased MELD-XI scores. RESULTS: During the follow-up period, 519 (20.6 %) patients died. Worsened MELD-XI score was independently associated with all-cause death [adjusted hazard ratio (aHR): 1.099; 95 % confidence interval (CI): 1.061-1.138; p < 0.001]. CR participation was associated with low mortality, even in the increased MELD-XI score group (aHR: 0.498; 95 % CI: 0.333-0.745; p < 0.001). Trajectory of the MELD-XI score was not associated with physical function changes. There were no time by MELD-XI score interaction effects on handgrip strength (p = 0.084), leg strength (p = 0.082), walking speed (p = 0.583), and 6-min walking distance (p = 0.833) in patients participating in outpatient CR. CONCLUSIONS: Hepato-renal dysfunction predicts high mortality. CR participation may be helpful for a better prognosis of patients with HF and hepato-renal dysfunction.