Drafting behaviors in fish induced by a local pressure drop around a hydrofoil model.

Fish schooling has the improvement in hydrodynamic propulsive efficiency through the interaction of flow field induced by fish bodies and tail beat. Such energy-saving behaviors due to flow interactions also occur with changes in the flow field caused by structures. We examined the differences between a live fish swimming around a streamlined hydrofoil model prepared to represent fish body and swimming alone in a flow tank. We observed that the fish can remain in the same place without tail beating. It called "drafting" behavior. The analysis of fish drafting showed that fish obtained thrust using a local pressure drop caused by the high velocity flow even in the vicinity of the hydrofoil model at an angle of attack α of 10° to 20°without flow separation, and fish balanced forces by using an α of fish body. This tendency was confirmed in the model experiment using a two-axis load cell, and the forces acting on the fish body was the smallest value when the fish model was placed in the same conditions as a live fish experiment. We also confirmed by simulation and found that the α of fish body generated lift force and counteract the suction force. Above results indicate that a fish can balance the anterior-posterior and lateral direction forces by using a local pressure drop around a hydrofoil model as suction force, and using angle of attack on its body, thereby realizing drafting.

Peak atrial longitudinal strain represents atrial fibrillation burden in daily practice: clinical implication of routine left atrial strain measurements.

BACKGROUND: Usefulness of left atrial (LA) strain measurements using speckle tracking echocardiography has been reported in various clinical settings. However, clinical implication of routine LA strain measurements in daily practice remains unclear. The purpose of this study was to evaluate clinical utility of routine LA strain measurements in daily practice. METHODS: From January 6, 2020 to December 28, 2021, 338 consecutive patients underwent echocardiography in Takagi Cardiology Clinic, and all comers were enrolled to the study. Echocardiographic measurements including peak atrial longitudinal strain (PALS) measurement using speckle tracking echocardiography were attempted in all patients. RESULTS: PALS was obtained in 335 patients (age 71 ± 16 years, male 43%, hypertensive 74%), and mean value was 22.3 ± 11.5%. PALS was progressively impaired with worsening atrial fibrillation (AF) burden. PALS in patients without AF, in patients with history of AF (paroxysmal AF &/or ablation therapy), and in patients with AF onsite were 26.8 ± 9.8%, 20.3 ± 7.9%, and 8.1 ± 3.3%, respectively (anova p < 0.0001). In patients without history of AF at the time of echocardiography, using cut-off value of 15.0% (i.e., mean + 2SD of PALS in AF patients), Kaplan-Meier analysis revealed that impaired PALS was associated with increased new-onset AF during follow-up period (log-rank p < 0.0001). CONCLUSION: In daily practice, PALS represents AF burden. Furthermore, impaired PALS is associated with increased new-onset AF. Therefore, routine LA strain measurements using speckle tracking echocardiography will be useful in risk stratification of AF in daily practice.

Hydrodynamical effect of parallelly swimming fish using computational fluid dynamics method.

Fish form schools because of many possible reasons. However, the hydrodynamic mechanism whereby the energy efficiency of fish schools is improved still remains unclear. There are limited examples of fish models based on actual swimming movements using simulation, and the movements in existing models are simple. Therefore, in this study, we analyzed the swimming behavior of Biwa salmon (Oncorhynchus sp., a salmonid fish) using image analyses and formulated its swimming motion. Moreover, computational fluid dynamics analysis was carried out using the formulated swimming motion to determine the fluid force acting on the fish body model with real fish swimming motion. The swimming efficiency of the fish model under parallel swimming was obtained from the calculated surrounding fluid force and compared for different neighboring distances. The flow field around the fish model was also examined. The swimming efficiency of two fish models swimming parallelly was improved by approximately 10% when they were separated by a distance of 0.4L, where L is the total length of the model. In addition, the flow field behind the fish body was examined under both inphase and antiphase conditions and at inter-individual distances of 0.8L and 1.2L. The apparent flow speed in the distance range of 0.5-2.0L from the midpoint of the snouts of the two individuals was lower than the swimming speed. The pressure distribution on the fish model showed an elevated pressure at the caudal fin. Interestingly, we obtained an isopleth map similar to that of a caudal peduncle. To avoid a negative thrust, the aft part of the body must be thin, as shown in the isopleth map obtained in this study.

Impaired global longitudinal strain in elderly patients with preserved ejection fraction is associated with raised post-exercise left ventricular filling pressure.

BACKGROUND: The purpose of this study was to evaluate whether impaired resting global longitudinal strain (GLS) in elderly patients with preserved left ventricular (LV) ejection fraction (EF) is associated with raised post-exercise LV filling pressure estimated by the ratio of early diastolic transmitral flow velocity to annulus velocity (E/e'). METHODS: Seventy elderly patients (age = 74 ± 6 years, male 40 patients) who underwent treadmill stress echocardiography were studied. All patients had normal sinus rhythm, normal LV wall motion at rest, and had preserved LVEF ≥ 50%. Patients with exercise induced wall motion abnormality were not included. GLS at rest was measured using automated functional imaging. RESULTS: Twenty-four of the 70 patients had raised post-exercise LV filling pressure indicated by septal E/e' ≥ 15.0. Patients with raised post-exercise LV filling pressure had smaller resting GLS than that in patients without it (- 16.9 ± 1.8 vs. - 19.6 ± 2.5%, respectively, p < 0.0001). Downward stepwise multivariate logistic regression analysis demonstrated that resting GLS was one of independent predictors of raised post-exercise E/e'. Receiver operating characteristic (ROC) curve analysis had demonstrated that optimal cutoff point for resting GLS to predict raised post-exercise E/e' was - 17.8% (sensitivity 83.3%, specificity 80.4%, respectively), and the area under the ROC curve was 0.820. CONCLUSION: In elderly patients with preserved LVEF and without obvious myocardial ischemia, impaired resting GLS at rest is associated with raised post-exercise LV filling pressure estimated by E/e' ≥ 15.0.

Diastolic stress echocardiography.

Evaluation of diastolic dysfunction and diagnosis of heart failure with preserved ejection fraction (HFpEF) by echocardiography are routinely performed at rest. However, many patients with modest HFpEF develop symptoms such as dyspnea only during exercise. Therefore, echocardiographic analysis at rest could be insufficient to identify these patients. Recent studies have demonstrated the utility of diastolic stress echocardiography to evaluate diastolic dysfunction during exercise. This review attempts to summarize and discuss current studies in diastolic stress echocardiography.

Comparison of effects of sitagliptin and voglibose on left ventricular diastolic dysfunction in patients with type 2 diabetes: results of the 3D trial.

BACKGROUND: Left ventricular (LV) diastolic dysfunction is frequently observed in patients with type 2 diabetes. Dipeptidyl peptidase-4 inhibitor (DPP-4i) attenuates postprandial hyperglycemia (PPH) and may have cardio-protective effects. It remains unclear whether DPP-4i improves LV diastolic function in patients with type 2 diabetes, and, if so, it is attributable to the attenuation of PPH or to a direct cardiac effect of DPP-4i. We compared the effects of the DPP-4i, sitagliptin, and the alpha-glucosidase inhibitor, voglibose, on LV diastolic function in patients with type 2 diabetes. METHODS: We conducted a prospective, randomized, open-label, multicenter study of 100 diabetic patients with LV diastolic dysfunction. Patients received sitagliptin (50 mg/day) or voglibose (0.6 mg/day). The primary endpoints were changes in the e' velocity and E/e' ratio from baseline to 24 weeks later. The secondary efficacy measures included HbA1c, GLP-1, lipid profiles, oxidative stress markers and inflammatory markers. RESULTS: The study was completed with 40 patients in the sitagliptin group and 40 patients in the voglibose group. There were no significant changes in the e' velocity and E/e' ratio from baseline to 24 weeks later in both groups. However, analysis of covariance demonstrated that pioglitazone use is an independent factor associated with changes in the e' and E/e' ratio. Among patients not using pioglitazone, e' increased and the E/e' ratio decreased in both the sitagliptin and voglibose groups. GLP-1 level increased from baseline to 24 weeks later only in the sitagliptin group (4.8 ± 4.7 vs. 7.3 ± 5.5 pmol/L, p < 0.05). The reductions in HbA1c and body weight were significantly greater in the sitagliptin group than in the voglibose group (-0.7 ± 0.6 % vs. -0.3 ± 0.4, p < 0.005; -1.3 ± 3.2 kg vs. 0.4 ± 2.8 kg, p < 0.05, respectively). There were no changes in lipid profiles and inflammatory markers in both groups. CONCLUSIONS: Our trial showed that sitagliptin reduces HbA1c levels more greatly than voglibose does, but that neither was associated with improvement in the echocardiographic parameters of LV diastolic function in patients with diabetes. TRIAL REGISTRATION: Registered at http://www.umin.ac.jp under UMIN000003784.

DPP-4 inhibitor and alpha-glucosidase inhibitor equally improve endothelial function in patients with type 2 diabetes: EDGE study.

BACKGROUND: Alpha glucosidase inhibitor (GI) attenuates postprandial hyperglycemia (PPH) and reduces the risk of cardiovascular events in patients with impaired glucose tolerance or type 2 diabetes. Dipeptidyl peptidase 4 (DPP-4) inhibitors also attenuate PPH. PPH is one of the factors leading to endothelial dysfunction which is an early event in the pathogenesis of atherosclerosis. Furthermore, DPP-4 inhibitors protect endothelial function through a GLP-1-dependent mechanism. However, the impact of these two types of drugs on endothelial dysfunction in patients with type 2 diabetes has not been fully elucidated. We compared the effects of sitagliptin, a DPP-4 inhibitor, and voglibose, an alpha GI, on endothelial function in patients with diabetes. METHODS: We conducted a randomized prospective multicenter study in 66 patients with type 2 diabetes who did not achieve the treatment goal with sulfonylurea, metformin or pioglitazone treatment; 31 patients received sitagliptin treatment and 35 patients, voglibose treatment. The flow-mediated dilatation (FMD) of the brachial artery was measured in the fasting state at baseline and after 12 weeks of treatment. The primary endpoint was a change in FMD (ΔFMD) from the baseline to the end of follow-up. The effects of sitagliptin and voglibose on FMD were assessed by ANCOVA after adjustment for the baseline FMD, age, sex, current smoking, diabetes duration and body mass index. Secondary efficacy measures included changes in HbA1c, GIP, GLP-1, C-peptide, CD34, lipid profile, oxidative stress markers, inflammatory markers and eGFR and any adverse events. RESULTS: ΔFMD was significantly improved after 12 weeks of treatment in both groups, and there was no significant difference in ΔFMD between the two groups. There were no significant differences in changes in HbA1c, GIP, GLP-1, C-peptide, lipid profile, oxidative stress marker, inflammatory marker and eGFR between the two groups. Compared with voglibose, sitagliptin significantly increased the circulating CD34, a marker of endothelial progenitor cells. Adverse events were observed in 5 patients in only the voglibose group (diarrhea 1, nausea 1, edema 2 and abdominal fullness 1). CONCLUSIONS: Sitagliptin improved endothelial dysfunction just as well as voglibose in patients with type 2 diabetes. Sitagliptin had protective effects on endothelial function without adverse events. TRIAL REGISTRATION: registered at http://www.umin.ac.jp/ctrj/ under UMIN000003951.

Low diastolic wall strain is associated with raised post-exercise E/E' ratio in elderly patients without obvious myocardial ischemia.

BACKGROUND: It has been reported that the diastolic wall strain (DWS) inversely correlates with the myocardial stiffness constant. The ratio of early diastolic transmitral flow velocity to annulus velocity (E/E') correlates with the left ventricular (LV) filling pressure. Increased LV wall stiffness is thought be associated with increased LV filling pressure after exercise. The purpose of this study was to evaluate the correlation between the DWS and post-exercise E/E' in elderly patients without obvious myocardial ischemia. METHODS: Fifty-eight elderly patients (age = 74 ± 6 years) who underwent treadmill stress echocardiography were studied. All patients had normal LV wall motion at rest, and patients with exercise-induced wall motion abnormality were excluded. The DWS was calculated as follows: DWS = (PWTs - PWTd)/PWTs, where PWTs is the LV posterior wall thickness at end-systole and PWTd is that at end-diastole. As previously reported, DWS ≤ 0.33 was defined as low DWS and E/E' ≥15.0 was defined as a marker of increased LV filling pressure. RESULTS: Eighteen patients had low DWS. Patients with low DWS had greater post-exercise E/E' (17.9 ± 3.2 vs. 12.8 ± 3.3, p < 0.0001). The DWS was inversely and strongly correlated with post-exercise E/E' (r (2) = 0.534, p < 0.0001). Low DWS predicted the development of raised post-exercise E/E' ≥15.0 with a positive predictive value of 94 % and a negative predictive value of 85 %. CONCLUSION: In elderly patients without obvious myocardial ischemia, the DWS correlates strongly and inversely with post-exercise E/E'. Patients with low DWS were likely to develop raised E/E' after exercise.

Elevated left ventricular filling pressure estimated by E/E' ratio after exercise predicts development of new-onset atrial fibrillation independently of left atrial enlargement among elderly patients without obvious myocardial ischemia.

OBJECTIVE: To determine whether elevated left ventricular (LV) filling pressure estimated by raised Doppler E velocity to tissue Doppler E' velocity ratio (E/E') after exercise is associated with increased risk of new-onset atrial fibrillation (AF) in non-ischemic elderly patients. BACKGROUND: Prognostic importance of exercise induced LV diastolic dysfunction remains uncertain. PATIENTS AND METHODS: We studied 147 elderly patients (73 ± 5 years) who underwent treadmill stress echocardiography. Patients with exercise induced LV wall motion abnormality were not included. Doppler and tissue Doppler measurements were done before treadmill exercise and immediately after the post-stress image acquisition, and E/E' ratio was measured. Raised E/E' was defined as E/E'≥ 15, and left atrial (LA) enlargement was defined as LA volume index ≥ 34 ml/m(2). Using Cox proportional hazards regression analysis, predictor of new-onset AF was determined. Using Kaplan-Meier analysis, we evaluated association between raised post-exercise E/E' or LA enlargement with new-onset AF. RESULTS: During the follow-up period (median=67 months), there were 25 new-onset AF. Cox proportional hazards regression analysis demonstrated that male gender [hazard ratio (HR) 3.294; p=0.0117], LA enlargement (HR 3.576; p=0.0017), and raised post-exercise E/E' (HR 3147; p=0.0068) were the best predictors of new-onset AF. Kaplan-Meier survival plot demonstrated that patients with both LA enlargement and raised post-exercise E/E' developed new-onset AF most frequently. There was no significant difference in outcome between patients with isolated raised post-exercise E/E' or isolated LA enlargement. CONCLUSIONS: Raised E/E' ratio after exercise provides significant prognostic information for predicting new-onset AF in non-ischemic elderly patients. This prognostic value of raised post-exercise E/E' is independent of and incremental to the LA enlargement.

Hydrodynamics and energy-saving swimming techniques of Pacific bluefin tuna.

Weihs theoretically revealed that during the movement of fish with negative buoyancy, more kinetic energy is saved in the glide and upward (GAU) swimming mode than in the continuous horizontal swimming mode. Because kinetic energy saving depends on dynamic parameters such as the drag and lift of the body, the effects of variations in these parameters on energy saving for different species remain unknown. Here, the kinetic energy saving of Pacific bluefin tuna (PBT), Thunnus orientalis, exhibiting the GAU swimming mode was investigated. The dynamic properties of PBT were estimated by carrying out CFD analysis. The CFD model was produced by using a three-dimensional laser surface profiler, and the model was controlled such that it exhibited swimming motion similar to that of a live PBT swimming in a flume tank. The drag generated by tail beating, which significantly affects the kinetic energy during motion, was twice that generated in the glide mode. The faster the upward swimming speed, the lesser is the kinetic energy saving; therefore, when the upward swimming speed is more than twice the glide speed, there is no gain in the GAU mode. However, when SMR (Standard Metabolic Rate) is considered, if the energy based on SMR is assumed to be 30% of the total energy spent during motion, the most efficient upward swimming speed is 1.4 times the glide speed. The GAU swimming mode of PBT leads to energy saving during motion, and the upward swimming speed and the lift force produced by the pectoral fins for the most efficient drive are unique for different species of different sizes.

Therapies targeting inflammation after stent implantation.

Since the introduction of coronary vessel scaffold by metallic stent, percutaneous coronary intervention has become widely performed all over the world. Although drug-eluting stent technology has further decrease the incidence of in-stent restenosis, there still remaining issues related to stent implantation. Vessel inflammation is one of the causes that may be related to stent restenosis as well as stent thrombosis. Therefore, systemic therapies targeting inflammation emerged as adjunctive pharmacological intervention to improve outcome. Statins, corticosteroids, antiplatelets, and immunosuppresive or anti-cancer drugs are reported to favorably impact outcome after bare-metal stent implantation. In type 2 diabetic patients, pioglitazone may be the most promising drug that can lower neointimal proliferation and, as a result, lower incidence of restenosis and target lesion revascularization. On the other hand, several new stent platforms that might decrease inflammatory response after drug-eluting stent implantation have been introduced. Because durable polymer used in the first generation drug-eluting stents are recognized to be responsible for unfavorable vessel response, biocompatible or bioabsorbable polymer has been introduce and already used clinically. Furthermore, polymer-free drug-eluting stent and bioresorbable scaffold are under investigation. Although vessel inflammation may be reduced by using these new drug-eluting stents or scaffold, long-term impact needs to be investigated further.

Patient with pseudo-retrograde coronary flow in the normal right coronary artery and left circumflex artery: pitfall of retrograde coronary flow to detect coronary artery occlusion.

A 75-year-old lady with hypertension and paroxysmal atrial fibrillation underwent echocardiography to evaluate cardiac function. Transthoracic Doppler echocardiography revealed retrograde coronary flow in the right coronary artery (RCA) and left circumflex artery (LCX). Computed tomographic coronary angiography demonstrated normal but tortuous coronary arteries. This tortuosity of the coronary arteries was thought be a cause of pseudo-retrograde coronary flow in the RCA and LCX. The present case demonstrates a pitfall of retrograde coronary flow for the detection of coronary artery occlusion in daily practice.

Newly diagnosed glucose intolerance and prognosis after acute myocardial infarction: comparison of post-challenge versus fasting glucose concentrations.

BACKGROUND: Recent studies have demonstrated that newly diagnosed glucose intolerance is common among patients with acute myocardial infarction (AMI). The purpose of this study was to assess the long-term clinical cardiovascular outcomes in participants with AMI with abnormal fasting glucose compared with normal fasting glucose and an abnormal oral glucose tolerance test (OGTT) compared with a normal OGTT. METHODS: A prospective study was performed in 275 consecutive patients with AMI, 85 of whom had pre-diagnosed diabetes mellitus (DM). Those without DM were divided into two groups based on the 75 g OGTT at the time of discharge. Abnormal glucose tolerance (AGT) was defined as 2 h glucose ≥140 mg/dl; 78 patients had normal glucose tolerance (NGT) and 112 had AGT. The same patients were also reclassified into the normal fasting glucose group (NFG; n=168) or the impaired fasting glucose group (IFG; n=22). The association between the glucometabolic status and long-term major adverse cardiovascular event rates was evaluated. RESULTS: Kaplan-Meier survival curves showed that the AGT group had a worse prognosis than the NGT group and an equivalent prognosis to the DM group (p<0.0005). Cox proportional hazard model analysis showed that the HR of AGT to NGT for major adverse cardiovascular event rates was 2.65 (95% CI 1.37 to 5.15, p=0.004) while the HR of DM to NGT was 3.27 (1.68 to 6.38, p=0.0005). However, Cox HR of IFG to NFG for major adverse cardiovascular event rates was 1.83 (0.86 to 3.87), which was not significant. CONCLUSION: In patients with AMI, an abnormal OGTT is a better risk factor for future adverse cardiovascular events than impaired fasting blood glucose.

Altered trans-mitral flow velocity pattern after exercise predicts development of new-onset atrial fibrillation in elderly patients with impaired left ventricular relaxation at rest: prognostic value of diastolic stress echocardiography.

OBJECTIVE: This study attempted to determine whether exercise induced left ventricular (LV) diastolic dysfunction estimated by altered trans-mitral flow (TMF) velocity pattern after exercise is associated with increased risk of cardiac events including new-onset atrial fibrillation (AF) in elderly patients with impaired LV relaxation at rest. BACKGROUND: Diastolic stress echocardiography has been applied to evaluate LV diastolic function during and post-exercise. Prognostic importance of exercise-induced diastolic dysfunction remains uncertain. PATIENTS AND METHODS: We studied 126 patients (70±5 years; 70 males) who underwent treadmill stress echocardiography. Doppler measurements were done before exercise and immediately after the post-stress image acquisition, and the ratio between early (E) and atrial (A) TMF velocities was measured. Patients with impaired LV relaxation (E/A<1.0) at rest were studied. Altered TMF velocity pattern was present when patients with E/A<1.0 at rest developed E/A≥1.0 after exercise. Primary endpoints for follow-up were combination of major cardiac events and new-onset AF. RESULTS: There were 42 patients with altered TMF velocity pattern after exercise. During the 5-year follow-up period, there were 30 cardiac events including 13 new-onset AF. Kaplan-Meier survival plot demonstrated that altered TMF velocity pattern after exercise is associated with increased risk of cardiac events (p<0.0001) including development of new-onset AF (p=0.0003). Cox hazard ratio analysis demonstrated that altered TMF velocity pattern after exercise was the best predictor of cardiac events (hazard ratio 3.939; 95%confidence interval 1.662-9.337; p=0.0018). CONCLUSIONS: Altered TMF velocity pattern after exercise provides significant prognostic information for predicting cardiac events including new-onset AF in elderly patients with impaired left ventricular relaxation at rest.

A patient came back with retrograde coronary flow in the distal right coronary artery 2 years after coronary intervention: clinical significance of retrograde coronary flow to detect coronary artery occlusion.

A 69-year-old male patient, who had a history of coronary stent implantation to the proximal right coronary artery (RCA), presented with exertional chest pain. Transthoracic Doppler echocardiography revealed retrograde coronary flow in the distal RCA, and treadmill stress echocardiography revealed inducible myocardial ischemia in the inferior and posterior segments. Coronary angiography demonstrated a severe stenotic lesion with flow delay in the mid RCA and collateral circulation to the distal RCA from the left coronary artery. Detection of retrograde coronary flow in the distal RCA using transthoracic Doppler echocardiography is a useful method to diagnose subtotal occlusion of the RCA.

Employing relative entropy techniques for assessing modifications in animal behavior.

In order to make quantitative statements regarding behavior patterns in animals, it is important to establish whether new observations are statistically consistent with the animal's equilibrium behavior. For example, traumatic stress from the presence of a telemetry transmitter may modify the baseline behavior of an animal, which in turn can lead to a bias in results. From the perspective of information theory such a bias can be interpreted as the amount of information gained from a new measurement, relative to an existing equilibrium distribution. One important concept in information theory is the relative entropy, from which we develop a framework for quantifying time-dependent differences between new observations and equilibrium. We demonstrate the utility of the relative entropy by analyzing observed speed distributions of Pacific bluefin tuna, recorded within a 48-hour time span after capture and release. When the observed and equilibrium distributions are gaussian, we show that the tuna's behavior is modified by traumatic stress, and that the resulting modification is dominated by the difference in central tendencies of the two distributions. Within a 95% confidence level, we find that the tuna's behavior is significantly altered for approximately 5 hours after release. Our analysis reveals a periodic fluctuation in speed corresponding to the moment just before sunrise on each day, a phenomenon related to the tuna's daily diving pattern that occurs in response to changes in ambient light.

Evaluation of genetic trends and determination of the optimal number of cumulative records of parity required in reproductive traits in a Large White pig population.

Genetic improvement of the reproductive performance of pigs is important for pig breeding despite their low heritabilities. The objectives of this study were to investigate the effectiveness of selection concerning reproductive traits and to determine the optimal number of parity records required for accurate estimation of breeding values (BVs) in the open population of a commercial pig breeding company. The study used records of 2220 purebred Large White pigs (9845 litters) farrowed between 1998 and 2009 in the two herds of the Pacific Ocean Breeding Co. Ltd. The traits studied included farrowing interval (FI), total number of piglets at birth (TNB), average weaning weight per litter (AWW), and raising rate (RR). A statistical model was applied to the 4-trait repeatability animal model. The heritabilities of FI, TNB, AWW and RR were low. The genetic trends in TNB (h(2) = 0.09) showed approximately 1.0 increase in 6 years from 2003 to 2008. The predicted error variances indicated that up to fourth parity records are necessary for accurate genetic evaluation. The present study results indicated that even reproductive traits with low heritability can be improved.

Diastolic stress echocardiography in Japanese elderly patients: prevalence and features of patients with elevated left ventricular filling pressure after treadmill stress.

PURPOSE: This study attempted to evaluate the prevalence and features of elderly patients with elevated post-exercise left ventricular (LV) filling pressure in Japan. BACKGROUND: Previous studies have validated that LV filling pressure during exercise can be estimated non-invasively by the Doppler index of diastolic filling (E/E'), and diastolic stress echocardiography has been promoted. There is limited information about diastolic stress echocardiography in Japan. METHODS: Three hundred ten elderly patients aged ≥60 years who underwent treadmill stress echocardiography were studied. Patients with ischemic response were excluded. Doppler measurements were made before and immediately after the treadmill stress, and patients were divided into two groups regarding post-exercise E/E' with cutoff values of 15. Clinical and echocardiographic characteristics were compared between the two groups. RESULTS: One-third (33.9%) of the patients presented elevated post-exercise LV filling pressure indicated by E/E' ≥15. Patients with an elevated post-exercise E/E' were older (p = 0.0052), had a greater mean body mass index (p = 0.0459), were more likely to have an abnormal glucose tolerance (p = 0.0059), had a greater LV mass index (p = 0.0383), a greater left atrial volume index (p = 0.0042), and a higher E/E' value at rest (p < 0.0001). CONCLUSION: One-third of the Japanese elderly patients who were referred for treadmill stress echocardiography and not limited by ischemia presented elevated post-exercise LV filling pressure indicated by E/E' ≥15. These patients are likely to have clinical and echocardiographic characteristics of heart failure with preserved ejection fraction.