Usefulness of the predicted percentage ventilatory efficiency for carbon dioxide output during exercise in patients with chronic heart failure.

The ventilatory efficiency for carbon dioxide output ([Formula: see text]CO2) during exercise, as measured by the minute ventilation vs. [Formula: see text]CO2 slope ([Formula: see text]E vs. [Formula: see text]CO2 slope), is a powerful prognostic index in patients with chronic heart failure (CHF). This measurement is higher in women than in men, and it increases with age. This study aimed to investigate the usefulness of the predicted value of the percentage [Formula: see text]E vs. [Formula: see text]CO2 slope (%[Formula: see text]E vs. [Formula: see text]CO2 slope) as a prognostic index in patients with CHF. A total of 320 patients with CHF and a left ventricular ejection fraction (LVEF) < 45% (male, 85.6%; mean age, 64.6 years) who underwent symptom-limited cardiopulmonary exercise tests using a cycle ergometer were included in the study. The %[Formula: see text]E vs. [Formula: see text]CO2 was calculated using predictive formulae based on age and sex. Cardiovascular-related death was defined as the primary endpoint. The mean follow-up duration was 7.5 ± 3.3 years. Of 101 patients who died during the study period, 75 experienced cardiovascular-related deaths. The average [Formula: see text]E vs. [Formula: see text]CO2 slope was 32.8 ± 8.0, and the average %[Formula: see text]E vs. [Formula: see text]CO2 slope was 119.6 ± 28.2%. The cumulative incidence of cardiovascular-related death after 10 years of follow-up were 44.7% (95% CI 34.4-54.6%) in patients with %[Formula: see text]E vs. [Formula: see text]CO2 slope > 120 and 15.0% (95% CI 9.4-21.8%) in patients with %[Formula: see text]E vs. [Formula: see text]CO2 slope ≤ 120. The multivariate Cox regression analysis indicated that a %[Formula: see text]E vs. [Formula: see text]CO2 slope > 120 was an independent predictor of cardiovascular-related death (adjusted hazard ratio, 3.24; 95% confidence interval 1.65-6.67; p < 0.01). The %[Formula: see text]E vs. [Formula: see text]CO2 slope can be used for risk stratification in patients with CHF and an LVEF < 45%.

Age- and sex-stratified normal values for circulatory and ventilatory power during ramp exercise derived from a healthy Japanese population.

Circulatory power (CP) and ventilatory power (VP), obtained by cardiopulmonary exercise testing (CPX), have been suggested to be excellent prognostic markers for heart failure. However, the normal values of these parameters in healthy Japanese populations remain unknown; thus, we aimed to investigate these values in such a population. A total of 391 healthy Japanese participants, 20-78 years of age, underwent CPX with a cycle ergometer with ramp protocols. Systolic blood pressure (SBP), heart rate, oxygen uptake ([Formula: see text]O2) at peak exercise, and the slope of minute ventilation ([Formula: see text]E) versus carbon dioxide ([Formula: see text]CO2) ([Formula: see text]E vs. [Formula: see text]CO2 slope) were measured. CP was calculated by multiplying the peak [Formula: see text]O2 and SBP values, and VP was calculated by dividing the peak SBP value by the [Formula: see text]E versus [Formula: see text]CO2 slope. For males and females, the average CP values were 6119 ± 1280 (mean ± standard deviation) and 4775 ± 914 mmHg·mL/min/kg, respectively (p < 0.001). The average VP values for males and females were 8.0 ± 1.3 and 6.9 ± 1.3 mmHg (p < 0.001). CP decreased with age in both sexes. VP increased with age in females, with no significant change in males. We calculated the normal values for CP and VP in a healthy Japanese population. The results can contribute to the evaluation of patients' CPX results as a reference.

Hospital-Acquired Functional Decline and Clinical Outcomes in Older Patients Undergoing Transcatheter Aortic Valve Implantation.

BACKGROUND: This study aimed to assess the relationship between hospital-acquired functional decline and the risk of mid-term all-cause death in older patients undergoing transcatheter aortic valve implantation (TAVI).Methods and Results:In total, 463 patients (mean age 85 years, interquartile range [IQR]: 82, 88) undergoing elective TAVI at Sakakibara Heart Institute between 2010 and 2018, who were followed up for 3 years, were enrolled in the study. Hospital-acquired functional decline after TAVI, which was defined by at least a 1-point decrease on the Short Physical Performance Battery before discharge compared to the preoperative score, was assessed. A total of 113 patients (24.4%) showed hospital-acquired functional decline after TAVI, and 50 (11.3%) patients died over a mean follow-up period of 1.9±0.8 years. Kaplan-Meier survival curves indicated that hospital-acquired functional decline was significantly associated with all-cause mortality (log-rank test, P=0.001). On multivariate Cox regression analysis, hospital-acquired functional decline was associated with a higher risk of all-cause mortality (OR 2.108, 95% CI 1.119-3.968, P=0.021) independent of sex, body mass index, advanced chronic kidney disease, and preoperative frailty, as assessed by the modified essential frail toolkit. CONCLUSIONS: Hospital-acquired functional decline is associated with mid-term all-cause mortality in older patients following TAVI. Trajectory of functional status is a vital sign, and it is useful for risk stratification in older patients following TAVI.

Active Participation in Outpatient Cardiac Rehabilitation Is Associated With Better Prognosis After Coronary Artery Bypass Graft Surgery　- J-REHAB CABG Study.

BACKGROUND: There is little evidence regarding the effect of outpatient cardiac rehabilitation (CR) on exercise capacity or the long-term prognosis in patients after coronary artery bypass graft surgery (CABG). This study aimed to determine whether participation in outpatient CR improves exercise capacity and long-term prognosis in post-CABG Japanese patients in a multicenter cohort.Methods and Results:We enrolled 346 post-CABG patients who underwent cardiopulmonary exercise testing during early (2-3 weeks) and late (3-6 months) time points after surgery. They formed the Active (n=240) and Non-Active (n=106) CR participation groups and were followed for 3.5 years. Primary endpoint was a major adverse cardiac event (MACE): all-cause death or rehospitalization for acute myocardial infarction/unstable angina/worsening heart failure. Peak oxygen uptake at 3-5 months from baseline was significantly more increased in Active than in Non-Active patients (+26±24% vs. +19±20%, respectively; P<0.05), and the MACE rate was significantly lower in Active than Non-Active patients (3.4% vs. 10.5%, respectively; P=0.02). Multivariate Cox proportional hazard analysis showed that participation in outpatient CR was a significant prognostic determinant of MACE (P=0.03). CONCLUSIONS: This unique study showed that a multicenter cohort of patients who underwent CABG and actively participated in outpatient CR exhibited greater improvement in exercise capacity and better survival without cardiovascular events than their counterparts who did not participate.

The use of geographical analysis in assessing the impact of patients' home addresses on their participation in outpatient cardiac rehabilitation: a prospective cohort study.

PURPOSE: Geographical analysis is becoming a powerful tool for evaluating the quality of medical services and acquiring fundamental data for medical decision-making. Using geographical analysis, we evaluated the impact of the distance from patients' homes to the hospital on their participation in outpatient cardiac rehabilitation (OCR). METHODS: All patients hospitalized for percutaneous coronary intervention, coronary artery bypass grafting, valvular surgery, congestive heart failure, and aortic diseases were advised to participate in an OCR program after discharge. Using the dataset of our cohort study of OCR from 2004 to 2015 (n = 9,019), we used geographical analysis to investigate the impact of the distance from patients' homes to hospital on their participation in our OCR program. RESULTS: Patients whose road distance from home to hospital was 0-10 km, 10-20 km, and 20-30 km participated more in OCR than those whose road distance was ≧ 30 km (OR 4.34, 95% CI 3.80-4.96; OR 2.98, 95% CI 2.61-3.40; and OR 1.90, 95% CI 1.61-2.23, respectively). Especially in patients with heart failure, the longer the distance, the lesser the participation rate (P < .001). CONCLUSIONS: Using geographical analysis, we successfully evaluated the factors influencing patients' participation in OCR. This illustrates the importance of using geographical analysis in future epidemiological and clinical studies. TRIAL REGISTRATION: UMIN000028435.

Right ventricular dysfunction is associated with exercise intolerance and poor prognosis in ischemic heart disease.

Right ventricular (RV) function is a prognostic factor in ischemic heart disease (IHD) patients, although its correlations with exercise capacity and cardiac rehabilitation (CR) efficacy are unknown. We aimed to clarify how RV function was associated with exercise tolerance and efficacy of phase II CR in IHD patients. We retrospectively analyzed 301 consecutive IHD patients who underwent phase II CR. We defined RV dysfunction using a combination of RV fractional area change < 35%, tricuspid annular plane systolic excursion < 1.6 cm, and systolic velocity < 10 cm/s. Exercise capacity was assessed using cardiopulmonary testing. The relation between RV function and exercise capacity was analyzed. The all-cause death and major adverse cardiac events (MACE) were evaluated by survival curve. The RV dysfunction group (n = 121) showed impaired left ventricular (LV) systolic and diastolic function before CR contrary to the normal RV function group (n = 180). The presence of RV dysfunction significantly reduced %AT by 4% and %Peak[Formula: see text] by 9% before CR, but increases the degree of improvement in %Peak[Formula: see text] with CR, independent of LV systolic and diastolic function. Univariate analysis demonstrated that previous coronary artery bypass grafting (CABG) was negatively associated with all-cause deaths and MACE. Adjusted for previous CABG, poor prognosis correlated with coexisting LV and RV dysfunction (hazard ratio [HR] 3.91, 95% confidence interval [CI] 1.13-13.53, P = 0.03) and RV dysfunction alone (HR 3.08, 95% CI 1.01-9.37, P = 0.05). In IHD patients, RV dysfunction is associated with exercise intolerance before CR and increased MACE risk, independent of LV function. The CR was effective in patients with RV dysfunction.

Physical performance as a predictor of midterm outcome after mitral valve surgery.

The usefulness of performing physical function assessments for evaluating clinical outcomes after all cardiac surgeries has been reported. However, no studies have evaluated the relationship between physical function and prognosis in patients undergoing cardiac open surgery with mitral valve regurgitation (MR). This study investigated whether physical assessment, such as the short physical performance battery (SPPB), could predict unplanned readmission events in patients undergoing mitral valve surgery due to MR. SPPB could predict unplanned admission events in patients undergoing mitral valve surgery due to MR. This retrospective study included 168 patients who underwent mitral valve surgery. SPPB was performed 1.6 ± 1.1 days before surgery. The primary endpoint was unplanned readmission. The mean follow-up period was 762 ± 480 days, mean age was 73.8 ± 6.3 years, and 43% of the patients were women. Of the study patients, 46 required unplanned readmissions; 29 of these patients required readmissions within 1 year. Multivariate Cox regression analysis demonstrated that SPPB was independently associated with the primary endpoint. Receiver-operating characteristic analysis showed that SPPB had an area under the curve of 0.71, with an optimal cutoff of 11. The study patients were stratified into SPPB 12 or SPPB ≤ 11 groups. Kaplan-Meier analysis showed that the event-free rate was significantly lower in the SPPB ≤ 11 group (hazard ratio 3.8, 95% confidence interval 2.1-7.0; p < 0.001). SPPB was a useful tool for predicting unplanned readmission in patients undergoing mitral valve surgery due to MR.

Relation between change in exercise capacity and change in blood amino acids in patients with chronic heart failure.

[Purpose] Although cardiac rehabilitation (CR) is recommended for patients with chronic heart failure (CHF), adequate exercise effect cannot be obtained in elderly patients. Administration of amino acids (AA) to CHF patients has been reported to improve exercise capacity, but the changes in AA composition in plasma before and after CR had not been reported. This study aimed to measure plasma levels of AA in CHF patients and compare with values of normal range. In addition the relationship between the change of exercise capacity and AA were examined. [Subjects and Methods] Twelve CHF patients (60% males, aged 68 ± 12 years) were studied. The correction between the rates of changes in exercise capacity parameters and in plasma AA levels was investigated. [Results] Anaerobic threshold (AT) and peak oxygen uptake (VO2) improved significantly after CR. The AA profile showed no specific pattern, and citrulline (Cit) was the amino acid showing a significant positive correlation with exercise capacity (∆Cit vs. ∆AT: r=0.602, ∆Cit vs. ∆AT-work rate (WR): r=0.681, ∆Cit vs. ∆VO2/WR: r=0.635). A tendency of positive correlation was observed between ∆Cit and ∆peak VO2 (r=0.456). [Conclusion] The AA profile showed no specific pattern, but a relationship between change in exercise capacity and Cit were found.

Regional Clinical Alliance Path and Cardiac Rehabilitation After Hospital Discharge for Acute Myocardial Infarction Patients in Japan　- A Nationwide Survey.

BACKGROUND: The regional clinical alliance path (RCAP) after discharge from an acute-phase hospital is emerging as a tool for bridging acute-phase treatment and chronic-phase disease management. However, the optimal application of RCAP for acute myocardial infarction (AMI) remains unknown in Japan, and therefore a nationwide survey of hospitals was conducted. METHODS AND RESULTS: In 2009, questionnaires were sent to 1,240 cardiology training hospitals authorized by the Japanese Circulation Society. The response rate was 62.9% (780/1,240). Of the 780 responding hospitals, 708 treated AMI, and in these hospitals the number of AMI patients and percutaneous coronary intervention (PCI) procedures performed were, respectively, 59±52 and 200±206 per year. The implementation rate of emergency PCI was high (91%), but that of outpatient cardiac rehabilitation (OPCR) was very low (18%). The implementation rate of RCAP after AMI was significantly lower (10%) than after stroke (57%). Cardiac rehabilitation (CR) was adopted as part of RCAP in only 19% (13/70) of currently operating RCAP programs. CONCLUSIONS: This first Japanese nationwide survey of RCAP after AMI showed that in contrast to the broad dissemination of acute-phase invasive treatment for AMI, there was infrequent implementation of OPCR, RCAP after AMI, and RCAP including CR. It will be necessary to broaden the use of RCAP after AMI, including OPCR. (Circ J 2016; 80: 1750-1755).

Waon Therapy for Managing Chronic Heart Failure　- Results From a Multicenter Prospective Randomized WAON-CHF Study.

BACKGROUND: Waon therapy improves heart failure (HF) symptoms, but further evidence in patients with advanced HF remains uncertain. METHODS AND RESULTS: In 19 institutes, we prospectively enrolled hospitalized patients with advanced HF, who had plasma levels of B-type natriuretic peptide (BNP) >500 pg/ml on admission and BNP >300 pg/ml regardless of more than 1 week of medical therapy. Enrolled patients were randomized into Waon therapy or control groups. Waon therapy was performed once daily for 10 days with a far infrared-ray dry sauna maintained at 60℃ for 15 min, followed by bed rest for 30 min covered with a blanket. The primary endpoint was the ratio of BNP before and after treatment. In total, 76 Waon therapy and 73 control patients (mean age 66 years, men 61%, mean plasma BNP 777 pg/ml) were studied. The groups differed only in body mass index and the frequency of diabetes. The plasma BNP, NYHA classification, 6-min walk distance (6MWD), and cardiothoracic ratio significantly improved only in the Waon therapy group. Improvements in NYHA classification, 6MWD, and cardiothoracic ratio were significant in the Waon therapy group, although the change in plasma BNP did not reach statistical significance. No serious adverse events were observed in either group. CONCLUSIONS: Waon therapy, a holistic soothing warmth therapy, showed clinical advantages in safety and efficacy among patients with advanced HF.

Coronary atherosclerotic lesions in patients with a ruptured abdominal aortic aneurysm.

In this study, the coronary findings in 185 autopsy cases with a ruptured abdominal aortic aneurysm (AAA) from the Tokyo Medical Examiner's Office were examined and compared with those in 1,056 patients undergoing AAA repair at the University of Tokyo Hospital or Sakakibara Heart Institute (Tokyo, Japan). The number of cases with any significant coronary stenosis was significantly greater in the autopsy cases with a ruptured AAA than in the patients undergoing emergency repair of a ruptured AAA, suggesting that the low prevalence of CAD observed in patients undergoing emergency repair of a ruptured AAA was due to the survival bias before reaching hospital. In addition, we also found that significant coronary left main trunk stenosis was more frequent in CAD cases with a ruptured AAA than in those with an unruptured AAA, findings that suggest novel clinical implications. Large-scale prospective studies are warranted to confirm our findings and to clarify the pathophysiological relationship between coronary atherosclerosis and AAA status.

Predictors of mortality after emergency or elective repair of abdominal aortic aneurysm in a Japanese population.

In Japan, there has been virtually no study in a population large enough to definitively demonstrate a relationship between the preoperative clinical features and postoperative outcomes in patients undergoing abdominal aortic aneurysm (AAA) repair. The aim of this study was to determine the preoperative variables that significantly predict postoperative mortality after emergency or elective repair in Japanese patients with infrarenal AAA. In this retrospective cohort study, we assessed significant predictors of postoperative mortality in 1055 consecutive patients undergoing emergency (n = 186) or elective repair (n = 869) of an infrarenal AAA at the University of Tokyo Hospital or Sakakibara Heart Institute (Tokyo, Japan). Using logistic regression analysis, anemia (hemoglobin <9 g/dl), shock (systolic blood pressure <80 mmHg), and hypocholesterolemia (total cholesterol <120 mg/dl) were found to be independent preoperative predictors of 30-day mortality after emergency repair for ruptured AAA. The hazard ratio (HR) (95 % confidence interval) for these three predictors was 5.96 (1.70-20.84), 8.48 (1.47-49.02), and 7.31 (1.96-27.35), respectively. In the elective repair cases, no significant preoperative predictor of postoperative mortality could be identified either within or beyond 30 days of surgery. Hypocholesterolemia, anemia, and shock were found to be independent preoperative predictors of a postoperative high mortality rate in Japanese patients undergoing emergency repair for ruptured infrarenal AAA.

Associations of body mass index and hospital-acquired disability with post-discharge mortality in older patients with acute heart failure.

OBJECTIVES: To investigate the effect of hospital-acquired disability (HAD) on all-cause mortality after discharge according to the body mass index (BMI) in older patients with acute decompensated heart failure. METHODS: We included 408 patients aged ≥ 65 years who were hospitalized for acute decompensated heart failure and had undergone an acute phase of cardiac rehabilitation at the Sakakibara Heart Institute between April 2013 and September 2015 (median age: 82 years, interquartile range (IQR): 76-86; 52% male). Patients were divided into three groups based on BMI at hospital admission: underweight (< 18.5 kg/m2), normal weight (18.5 to 25 kg/m2), and overweight (≥ 25 kg/m2). HAD was defined as a decrease of at least five points at discharge compared to before hospitalization according to the Barthel Index. RESULTS: The median follow-up period was 475 (IQR: 292-730) days, and all-cause mortality during the follow-up period was 84 deaths (21%). According to multivariate Cox regression analysis, being underweight (HR: 1.941, 95% CI: 1.134-3.321,P = 0.016) or overweight (HR: 0.371, 95% CI: 0.171-0.803,P = 0.012), with normal BMI as the reference, and HAD (HR: 1.857, 95% CI: 1.062-3.250,P = 0.030) were independently associated with all-cause mortality. Patients with HAD exhibited a significantly lower cumulative survival rate in the underweight group (P = 0.001) and tended to have a lower cumulative survival rate in the normal weight group (P = 0.072). HAD was not significantly associated with cumulative survival in the overweight group (P = 0.392). CONCLUSIONS: BMI and HAD independently predicted all-cause mortality after discharge in older patients with acute decompensated heart failure. Furthermore, HAD was significantly associated with higher all-cause mortality after discharge, especially in the underweight group.

Study Design of the Japanese Association of Cardiac Rehabilitation Registry (J-CARRY)　- Protocol for a Prospective, Multicenter, Open Registry.

Background: Guidelines for the prevention and management of cardiovascular disease (CVD) highly recommend cardiac rehabilitation (CR) on the basis of abundant evidence of its effectiveness. However, the current understanding and dissemination of CR in Japan are far from sufficient. Methods and Results: The Japanese Association of Cardiac Rehabilitation Registry (J-CARRY) is an academic society-led prospective multicenter observational registry conducted by the Registration and Facility Accreditation System Committee of the Japanese Association of Cardiac Rehabilitation. Data are collected prospectively using an electronic data capture system. Items related to patients' clinical background and CR, as well as mortality and major adverse cardiac and cerebrovascular events, will be collected in all cases. This Registry started in May 2014, and the number of participating medical institutions is expected to increase to >30; the targeted number of cases exceeded 3,000 per year as of April 30, 2022. Focusing on late Phase II data collection is a novel and significantly different approach compared with previous studies. The results of this study are currently under investigation. Conclusions: J-CARRY will provide real-world data regarding the current status and prognosis of CVD in patients who undergo Phase II CR in Japan.

Cynical hostility, anger expression style, and acute myocardial infarction in middle-aged Japanese men.

Studies using American and European populations have demonstrated that high levels of anger/ hostility are predictive of coronary heart disease (CHD) mortality. However, Japanese studies did not show consistent relationship between anger/hostility and CHD. This study examines the association of cynical hostility and anger expression style with acute myocardial infarction (AMI) in middle-aged Japanese men through a case-control study. The patients with acute myocardial infarction (N = 96, mean age = 50.8 years) and the healthy participants in a health check-up program (N = 77, mean age = 50.3 years) were studied. Both groups completed the Cynicism Questionnaire (CQ) and the State-Trait Anger Expression Inventory (STAXI). The patients exhibited higher scores on CQ than the healthy controls. Logistic regression analyses controlling for biological risk factors revealed that the CQ score was associated with increased risk of AMI (OR = 1.11 [95% CI 1.00-1.22]). In addition, the score of Anger-control, a subscale of STAXI, was associated with decreased risk of AMI (OR = 0.75 [95% CI 0.62-0.92]). These results indicated that higher levels of cynical hostility increased the risk of AMI and that anger-control strategies could have some benefit in reducing the risk of AMI in middle-aged Japanese men.

Psoas Muscle Volume and Attenuation are Better Predictors than Muscle Area for Hospital Readmission in Older Patients after Transcatheter Aortic Valve Implantation.

OBJECTIVE: This study aimed to determine whether the psoas muscle volume (PMV) and its muscle attenuation (MA) are associated with hospital readmission after transcatheter aortic valve implantation (TAVI). METHOD: We included 113 older patients with aortic stenosis who underwent TAVI at Sakakibara Heart Institute (mean age 85 ± 5 years, 69% women). We measured PMV and psoas muscle area (PMA) as well as total muscle area (TMA) at the third lumbar vertebra using preoperative computed tomography (CT) images. The crude values of the PMV, PMA, and TMA were normalized by dividing by height squared. RESULTS: The median follow-up period was 724 days (interquartile range: 528-730 days), and there were 25 all-cause readmissions during the follow-up period (22% of all patients). In the multivariate Cox regression analysis adjusted for age, sex, and EuroSCORE II, the PMV and its MA and crude PMA were significantly associated with all-cause readmission [HR: 0.957 (0.930-0.985), p = 0.003, HR: 0.927 (0.862-0.997), p = 0.040], whereas the PMA and TMA and each MA were not (all p > 0.05). The groups with low PMV and MA had significantly higher incidences of all-cause readmission than that with high PMV and MA (log-rank test: p = 0.011). CONCLUSION: PMV and its MA measured from preoperative CT images were independent predictors of all-cause readmission in TAVI patients.

Hospitalization-Associated Disability After Cardiac Surgery in Elderly Patients　- Exploring the Risk Factors Using Machine Learning Algorithms.

Background: Hospitalization-associated disability (HAD) is associated with prolonged functional decline and increased mortality after discharge. Therefore, we examined the incidence and risk factors associated with HAD in elderly patients undergoing cardiac surgery in Japan. Methods and Results: We retrospectively examined 2,262 elderly patients who underwent elective cardiac surgery at Sakakibara Heart Institute. HAD was defined as a functional decline between time of admission and discharge measured by the Barthel Index. We analyzed clinical characteristics using machine learning algorithms to identify the risk factors associated with HAD. After excluding 203 patients, 2,059 patients remained, of whom 108 (5.2%) developed HAD after cardiac surgery. The risk factors identified were age, serum albumin concentration, estimated glomerular filtration rate, Revised Hasegawa's Dementia Scale, N-terminal pro B-type natriuretic peptide, vital capacity, preoperative Short Physical Performance Battery (SPPB) score, operation times, cardiopulmonary bypass times, ventilator times, length of postoperative intensive care unit stay, and postoperative ambulation start day. The highest incidence of HAD was found in patients with an SPPB score ≤9 and in those who started ambulation >6 days after surgery (76.9%). Conclusions: Several risk factors for HAD are components of frailty, suggesting that preoperative rehabilitation to reduce the risk of HAD is feasible. Furthermore, the association between HAD and a delayed start of ambulation reaffirms the importance of early mobilization and rehabilitation.

Ventilatory efficiency during ramp exercise in relation to age and sex in a healthy Japanese population.

BACKGROUND: The current understanding of ventilator efficiency variables during ramp exercise testing in the normal Japanese population is insufficient, and the responses of tidal volume (VT) and minute ventilation (V̇E) to the ramp exercise test in the normal Japanese population are not known. METHODS: A total of 529 healthy Japanese subjects aged 20-78 years underwent cardiopulmonary exercise testing using a cycle ergometer with ramp protocols. VT and V̇E at rest, at anaerobic threshold, and at peak exercise were determined. The slope of V̇E versus carbon dioxide (V̇CO2) (V̇E vs. V̇CO2 slope), minimum V̇E/V̇CO2, and oxygen uptake efficiency slope (OUES) were determined. RESULTS: For males and females in their 20 s, peak VT (VTpeak) was 2192 ± 376 and 1509 ± 260 mL (p < 0.001), peak V̇E (V̇Epeak) was 80.6 ± 18.7 and 57.7 ± 13.9 L/min (sex differences p < 0.001), the V̇E vs. V̇CO2 slope was 24.4 ± 3.2 and 25.7 ± 3.2 (p = 0.035), the minimum V̇E/V̇CO2 was 24.2 ± 2.3 and 27.0 ± 2.8 (p < 0.001), and the OUES was 2452 ± 519 and 1991 ± 315 (p < 0.001), respectively. VTpeak and V̇Epeak decreased with age and increased with weight and height. The V̇E vs. V̇CO2 slope and minimum V̇E/V̇CO2 increased with age, while conversely, the OUES decreased with age. CONCLUSIONS: We have established the normal range of VT and V̇E responses, the V̇E vs. V̇CO2 slope, the minimum V̇E/V̇CO2, and the OUES for a healthy Japanese population. Some of these parameters were influenced by weight, height, sex, and age. These results provide useful reference values for interpreting the results of cardiopulmonary exercise testing in cardiac patients.