Kentaro Kamiya

Quadriceps isometric strength as a predictor of exercise capacity in coronary artery disease patients

Background Quadriceps strength is related to exercise capacity in normal subjects and different patient populations, but the relationship between maximal quadriceps isometric strength (QIS) and different exercise capacity levels in coronary artery disease (CAD) patients has not been systematically evaluated yet. Method We studied 621 patients (60.6 ± 9.9 years, 538 males) with recent coronary artery bypass grafting or myocardial infarction, who underwent treadmill exercise testing, maximal QIS measurement (hand-held dynamometry), and coronary arteriography. Maximal QIS was expressed as absolute value (kg), %bodyweight, and %predicted maximum. Logistic regression was used to assess the relationship of maximal QIS, age, sex, number of diseased coronary vessels, peak systolic blood pressure, peak heart rate, brain natriuretic peptide, and left ventricular ejection fraction with 5, 7, and 10 estimated metabolic equivalents (eMETs) exercise capacity levels. Results Maximal QIS %bodyweight was the strongest predictor of exercise capacity in each eMETs category. Receiver-operating characteristics curves identified maximal QIS of 46, 51, and 59 % bodyweight as the best predictive cut offs for 5, 7 and 10 eMETs, respectively, with positive predictive values of 0.72, 0.66, and 0.67, respectively. Conclusions Maximal QIS is related with eMETs levels reached at exercise testing in CAD patients, and identified maximal QIS cut-off values for eMETs prediction may be used to set strength training goals according to patients’ needs with regard to habitual physical activity level. Hand-held dynamometry may meet the need of easiness of use and low cost required for strength evaluation in large-scale clinical trials.

Quadriceps Strength as a Predictor of Mortality in Coronary Artery Disease

BACKGROUND The purpose of this study was to investigate the prognostic value of quadriceps isometric strength (QIS) in coronary artery disease (CAD). METHODS The study population consisted of 1314 patients aged >30 years (64.7 ± 10.6 years, 1051 male) with CAD who were hospitalized for acute coronary syndrome or coronary artery bypass grafting. Maximal QIS was evaluated as a marker of leg strength and expressed relative to body weight (% body weight). The primary and secondary endpoints were all-cause death and cardiovascular (CV) death, respectively. RESULTS During a mean follow-up of 5.0 ± 3.5 years, corresponding to 6537 person-years, there were 118 all-cause deaths and 63 CV deaths. A higher QIS remained associated with decreased all-cause mortality and CV mortality risks (hazard ratio for increasing 10% body weight of QIS 0.77, 95% confidence interval 0.67-0.89, P < .001 for all-cause death; hazard ratio 0.66, 95% confidence interval 0.54-0.82, P < .001 for CV death) after adjustment for other prognostic factors. The inclusion of QIS significantly increased both continuous net reclassification improvement (cNRI) and integrated discrimination improvement (IDI) for all-cause death (cNRI: 0.25, P = .009; IDI: 0.007, P = .030) and CV death (cNRI: 0.34, P = .008; IDI: 0.013, P = .008). CONCLUSIONS A high level of quadriceps strength was strongly associated with a lower risk of both all-cause and CV mortality in patients with CAD. Evaluation of QIS offered incremental prognostic information beyond pre-existing risk factors.

Usefulness of pet ownership as a modulator of cardiac autonomic imbalance in patients with diabetes mellitus, hypertension, and/or hyperlipidemia.

Among patients with coronary artery disease, pet owners exhibit a greater 1-year survival rate than nonowners. Lifestyle-related diseases are well-known risk factors for coronary artery disease and induce imbalances in autonomic nervous activity. The purpose of the present study was to determine whether pet ownership modulates cardiac autonomic nervous activity imbalance in patients with lifestyle-related diseases such as diabetes mellitus, hypertension, and hyperlipidemia. A total of 191 patients (mean age 69 ± 8 years) were interviewed about their pet ownership status and were classified into pet owner and nonowner groups. After recording a 24-hour Holter electrocardiogram for heart rate variability analysis, frequency-domain and nonlinear-domain analyses were performed to determine the high-frequency (HF) and low-frequency (LF) components, LF/HF ratio, and entropy. The heart rate variability parameters were assessed for 24 hours, during the day (8.00 A.M. to 5.00 P.M.), and during the night (0:00 A.M. to 6.00 A.M.), and compared between the 2 groups. To evaluate the potential predictive factors for cardiac autonomic imbalance, univariate and multivariate analyses of HF and LF/HF were conducted for potential confounding variables. The pet owner group exhibited significantly greater HF(24h), HF(day), HF(night), entropy(24h), entropy(day), and entropy(night) and significantly lower LF/HF(24h) and LF/HF(night) compared to the nonowner group. On multivariate analysis, pet ownership was independently and positively associated with HF(24h,) HF(day), and HF(night) and inversely associated with LF/HF(24h) and LF/HF(night). In conclusion, these results suggest that pet ownership is an independent modulator of cardiac autonomic imbalance in patients with lifestyle-related diseases.

Complementary Role of Arm Circumference to Body Mass Index in Risk Stratification in Heart Failure.

OBJECTIVES This study was performed to investigate the complementary role of arm circumference to body mass index (BMI) in risk stratification of patients with heart failure (HF). BACKGROUND High BMI is associated with improved survival in patients with HF. However, it does not discriminate between fat and lean muscle as a predominant factor. METHODS BMI, waist circumference (WC), and mid-upper arm circumference (MUAC) were evaluated in 570 consecutive Japanese patients with HF (mean age 67.4 ± 14.0 years). Patients were stratified into low and high groups according to BMI, WC, and MUAC and combined into low- or high-BMI and low- or high-WC groups or low- or high-BMI and low- or high-MUAC groups. The endpoint was all-cause mortality. RESULTS Seventy deaths occurred over a median follow-up period of 1.5 years (interquartile range: 0.7 to 2.8 years). After adjusting for several pre-existing prognostic factors, including Seattle Heart Failure Score and exercise capacity, BMI (hazard ratio [HR]: 0.68; p = 0.016), WC (HR: 0.76; p = 0.044), and MUAC (HR: 0.52; p < 0.001) were all inversely associated with prognosis. Compared with the high-BMI/high-WC group, both the low-BMI/high-WC and low-BMI/low-WC groups showed comparably poorer prognosis. However, the low-BMI/low-MUAC group but not the low-BMI/high-MUAC group showed poorer prognosis than the high-BMI/high-MUAC group. Adding MUAC to BMI (0.70 vs. 0.63, p = 0.012) but not WC to BMI (0.64 vs. 0.63, p = 0.763) significantly increased the area under the curve on receiver-operating characteristic curve analysis. CONCLUSIONS MUAC, but not WC, plays a complementary role to BMI in predicting prognosis in patients with HF.

Repeated freeze–thaw cycles reduce the survival rate of osteocytes in bone-tendon constructs without affecting the mechanical properties of tendons

Frozen bone-patellar tendon bone allografts are useful in anterior cruciate ligament reconstruction as the freezing procedure kills tissue cells, thereby reducing immunogenicity of the grafts. However, a small portion of cells in human femoral heads treated by standard bone-bank freezing procedures survive, thus limiting the effectiveness of allografts. Here, we characterized the survival rates and mechanisms of cells isolated from rat bones and tendons that were subjected to freeze–thaw treatments, and evaluated the influence of these treatments on the mechanical properties of tendons. After a single freeze–thaw cycle, most cells isolated from frozen bone appeared morphologically as osteocytes and expressed both osteoblast- and osteocyte-related genes. Transmission electron microscopic observation of frozen cells using freeze-substitution revealed that a small number of osteocytes maintained large nuclei with intact double membranes, indicating that these osteocytes in bone matrix were resistant to ice crystal formation. We found that tendon cells were completely killed by a single freeze–thaw cycle, whereas bone cells exhibited a relatively high survival rate, although survival was significantly reduced after three freeze–thaw cycles. In patella tendons, the ultimate stress, Young’s modulus, and strain at failure showed no significant differences between untreated tendons and those subjected to five freeze–thaw cycles. In conclusion, we identified that cells surviving after freeze–thaw treatment of rat bones were predominantly osteocytes. We propose that repeated freeze–thaw cycles could be applied for processing bone-tendon constructs prior to grafting as the treatment did not affect the mechanical property of tendons and drastically reduced surviving osteocytes, thereby potentially decreasing allograft immunogenecity.

Effects of electrical muscle stimulation in a left ventricular assist device patient

a Department of Angiology and Cardiology, Kitasato University Graduate School of Medical Sciences, Sagamihara, Japan b Exercise Pathophysiology Laboratory, Cardiac Rehabilitation Division, S. Maugeri Foundation IRCCS, Scientific Institute of Veruno, Veruno (NO), Italy c Department of Rehabilitation, School of Allied Health Sciences, Kitasato University, Sagamihara, Japan d Department of Cardio-Angiology, Kitasato University School of Medicine, Sagamihara, Japan

Safety of neuromuscular electrical stimulation in patients implanted with cardioverter defibrillators.

Neuromuscular electrical stimulation (NMES) is one of the few exercise modes that have been confirmed to be effective for advanced heart failure patients. Previous clinical trials that verified the effects of NMES excluded patients with implantable cardioverter defibrillators (ICDs). We investigated whether NMES to leg muscles could be applied in heart failure patients implanted with ICDs. As a result, we found that NMES could be conducted without any instances of electromagnetic interference. NMES to leg muscles could be applied safely to ICD patients if the aforementioned common stimulation methods were used with sufficient monitoring during NMES.

Japanese Adaptation of the Stroke and Aphasia Quality of Life Scale-39 (SAQOL-39): Comparative Study among Different Types of Aphasia

BACKGROUND We have developed a Japanese version of the Stroke and Aphasia Quality of Life Scale-39 (SAQOL-39), designated as SAQOL-39-J, and used psychometric methods to examine its acceptability and reliability. METHODS The acceptability and reliability of SAQOL-39-J, which was developed from the English version using a standard translation and back-translation method, were examined in 54 aphasia patients using standard psychometric methods. The acceptability and reliability of SAQOL-39-J were then compared among patients with different types of aphasia. RESULTS SAQOL-39-J showed good acceptability, internal consistency (Cronbachs α score = .90), and test-retest reliability (intraclass correlation coefficient = .97). Brocas aphasia patients showed the lowest total scores and communication scores on SAQOL-39-J. CONCLUSIONS The Japanese version of SAQOL-39, SAQOL-39-J, provides acceptable and reliable data in Japanese stroke patients with aphasia. Among different types of aphasia, Brocas aphasia patients had the lowest total and communication SAQOL-39-J scores. Further studies are needed to assess the effectiveness of health care interventions on health-related quality of life in this population.

Gait speed has comparable prognostic capability to six-minute walk distance in older patients with cardiovascular disease

Background Although gait speed and six-minute walk distance are used to assess functional capacity in older patients with cardiovascular disease, their prognostic capabilities have not been directly compared. Methods The study population was identified from the Kitasato University Cardiac Rehabilitation Database and consisted of 1474 patients ≥60 years old with a mean age of 72.2 ± 7.1 years that underwent evaluation of both usual gait speed and six-minute walk distance in routine geriatric assessment between 1 June 2008–30 September 2015. Both gait speed and six-minute walk distance were determined on the same day at hospital discharge. Results Mean gait speed and six-minute walk distance in the whole population were 1.04 m/s and 381 m, respectively, and were strongly positively correlated (r = 0.80, p < 0.001). A total of 180 deaths occurred during a follow-up of 2.3 ± 1.9 years. After adjusting for confounding factors, both gait speed (adjusted hazard ratio per 0.1 m/s increase: 0.87, 95% confidence interval: 0.81–0.93, p < 0.001) and six-minute walk distance (adjusted hazard ratio per 10-metre increase: 0.96, 95% confidence interval: 0.94–0.97, p < 0.001) were independent predictors of all-cause mortality. There was no significant difference in prognostic capability between gait speed and six-minute walk distance (c-index: 0.64 (95% confidence interval: 0.60–0.69) and 0.66 (95% confidence interval: 0.61–0.70), respectively, p = 0.357). Conclusions Gait speed and six-minute walk distance showed similar prognostic predictive ability for all-cause mortality in older cardiovascular disease patients, indicating the potential utility of gait speed as a simple risk stratification tool in older cardiovascular disease patients.

Low ankle brachial index is associated with the magnitude of impaired walking endurance in patients with heart failure

BACKGROUND Measurement of the ankle brachial index (ABI) is a simple, noninvasive means of diagnosing peripheral arterial disease, and has been shown to be associated with mortality rate. Here, we examined the association between ABI and physical function in patients with heart failure (HF). METHODS The study population consisted of 524 admitted patients (67.2±13.9years, 343 males) with HF. Blood pressure and the ABI were determined by oscillometry. Prior to hospital discharge, ABI, 6-minute walking distance, walking velocity, handgrip strength, quadriceps isometric strength, and standing balance were determined. The 524 patients were divided according to ABI as follows: ABI≤0.90 (low ABI), ABI 0.91 to 0.99 (borderline ABI), and ABI 1.00 to 1.40 (normal ABI). RESULTS Lower ABI values were associated with shorter 6-minute walking distance (p trend=0.001), slower walking velocity (p trend=0.023), and poorer standing balance (p trend=0.048). There were no significant associations between ABI and handgrip strength or quadriceps isometric strength. After adjusting for potential confounders, patients with ABI≤0.90 had shorter 6-minute walking distance compared to those with ABI 1.00 to 1.40 (adjusted mean value: 344m vs. 395m, respectively, p<0.001). There were no significant differences in any of the other physical function parameters examined. CONCLUSIONS In patients with HF, low ABI is associated with the magnitude of impairment in walking endurance.