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.

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.

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.

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.

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.

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.

Strain measurements during adenosine triphosphate infusion before and after percutaneous coronary intervention.

BACKGROUND: In regional myocardial ischemia, contractile delay develops, which can be assessed by measuring time to peak strain (TPS) on tissue Doppler imaging. The aims of the present study were to clarify the usefulness of TPS measurements during adenosine triphosphate (ATP) stress in assessing myocardial ischemia and to evaluate whether prolongation of TPS disappears immediately after percutaneous coronary intervention (PCI) or not. METHODS AND RESULTS: A total of 26 patients underwent strain measurements before and after PCI. Corrected TPS for heart rate (TPSc) in target regions and in control regions were measured both at baseline and during ATP infusion. TPSc ratio was calculated as a ratio of TPSc during ATP stress to TPSc at baseline. TPSc in the target region significantly increased during ATP infusion before PCI, which was significantly longer than hyperemic TPSc in control regions. Accordingly, TPSc ratio in the target regions before PCI was significantly greater than that in control regions (1.22+/-0.17 vs 0.96+/-0.09, respectively, P<0.0001). Following PCI, the TPSc ratio in the target regions significantly decreased to 0.98+/-0.05 (P<0.0001). Receiver operating characteristic curve analysis provided a cut-off of 1.04 in TPSc ratio for detecting myocardial ischemia with a sensitivity of 93% and specificity of 93%. CONCLUSIONS: TPS measurements during ATP stress differentiated target from control myocardium before PCI. The prolongation of TPSc disappeared immediately after PCI.

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.

Coronary flow velocity pattern immediately after percutaneous coronary intervention as a predictor of complications and in-hospital survival after acute myocardial infarction.

BACKGROUND: Recently, it was reported that the degree of microvascular injury and left ventricular functional recovery during the chronic period can be predicted after treatment of the infarct-related artery based on the coronary flow velocity (CFV) pattern assessed using a Doppler guidewire. The aim of this prospective study was to examine whether the CFV pattern may predict complications and in-hospital survival after acute myocardial infarction (AMI). METHODS AND RESULTS: The study population consisted of 169 consecutive patients with a first anterior AMI successfully treated with percutaneous coronary intervention (PCI). We examined the CFV pattern immediately after PCI using a Doppler guidewire. In accordance with previous findings, we defined severe microvascular injury as a diastolic deceleration time < or =600 ms and the presence of systolic flow reversal. Patients were divided into two groups: those without severe microvascular injury (n=118; group 1) and those with severe microvascular injury (n=51; group 2). All of the patients who had cardiac rupture were in group 2. Congestive heart failure (CHF) was observed more frequently in group 2 than in group 1 (53% versus 8%, P<0.001). The in-hospital cardiac mortality rate was significantly higher in group 2 than in group 1 (18% versus 0%, P<0.001). Nine patients in group 2 died, 5 patients because of CHF and 4 patients because of cardiac rupture. CONCLUSIONS: These findings suggest that the CFV pattern is an accurate predictor of the presence or absence of complications and of in-hospital survival after AMI.

Assessment of coronary flow reserve by coronary pressure measurement: comparison with flow- or velocity-derived coronary flow reserve.

OBJECTIVES: This study sought to assess the reliability of pressure-derived coronary flow reserve (CFR) compared with flow- or velocity-derived CFR. BACKGROUND: Coronary flow reserve has been reported to have important clinical implications for the evaluation and treatment of coronary artery disease. METHODS: Using a pressure guide wire, coronary pressure distal to the stenosis was measured at rest and during hyperemia in seven dogs with various degrees of stenosis and in 30 patients with angina (29 and 34 stenoses in total, respectively). Pressure at the tip of the guiding catheter was also recorded with a fluid-filled transducer system. Pressure-derived CFR was calculated by the square root of the pressure gradient across the stenosis (DeltaP) during hyperemia divided by DeltaP at rest, using a proprietary software system. At the same time, coronary flow was monitored proximal to the stenosis with a flow meter in the experimental dogs, and coronary flow velocity distal to the stenosis was assessed using a Doppler guide wire in patients with angina. Flow-derived (or velocity-derived) CFR was compared with pressure-derived CFR. RESULTS: Except for one stenosis that showed no DeltaP at rest, a significant correlation was obtained between pressure- and flow-derived CFR in the animal study (y = 1.05x - 0.03, r = 0.92, p = 0.0001). A significant correlation was also seen between pressure- and velocity-derived CFR in the human study, except in three stenoses with no resting DeltaP (y = 0.70x + 0.37, r = 0.85, p = 0.0001). CONCLUSIONS: Similar to flow (or velocity) measurement, CFR can be assessed by pressure measurement, except in stenoses with minor resting DeltaP.

Targeted disruption of LIG-1 gene results in psoriasiform epidermal hyperplasia.

The gene encoding a transmembrane glycoprotein LIG-1, of which the extracellular region was organized with the leucine-rich repeats and immunoglobulin-like domains, was disrupted in mice by gene targeting. LIG-1-deficient mice developed a skin change on the tail and facial area after birth. The affected skin was histologically reminiscent of the epidermis in human common skin disease 'psoriasis'. LIG-1 was expressed in basal cells of the epidermis and outer root sheath cells of hair follicles in mice. Interestingly, the LIG-1 expression was apparently down-regulated in the psoriatic lesions, suggesting that LIG-1 inversely correlates with proliferative ability of epidermal keratinocytes.

Pioglitazone reduces neointimal tissue proliferation after coronary stent implantation in patients with type 2 diabetes mellitus: an intravascular ultrasound scanning study.

BACKGROUND: It has been reported that pioglitazone reduces neointimal hyperplasia after balloon-induced vascular injury in an experimental model. METHODS: To determine whether pioglitazone reduces neointimal tissue proliferation after coronary stent implantation in patients with type 2 diabetes mellitus, we studied 44 stented lesions in 44 patients with diabetes mellitus who underwent successful coronary stent implantation. Study patients were randomized into 2 groups: the pioglitazone group (23 patients with 23 lesions) and the control group (21 patients with 21 lesions). All patients underwent serial quantitative coronary angiography and serial intravascular ultrasound scanning studies. With a motorized pullback system, multiple image slices within the stent were obtained at every 1 mm. The stent area and lumen area were measured, and the neointimal area was calculated. Measurements were averaged over the number of selected image slices. The neointimal index was calculated as the averaged neointimal area divided by the averaged stent area multiplied by 100 (%). RESULTS: After 6 months of treatment, angiographic in-stent restenosis (17% vs 43%, respectively, P =.0994) and target lesion revascularization (13% vs 38%, respectively, P =.0835) were less frequent in the pioglitazone group than the control group; however, these differences did not reach significance. The intravascular ultrasound scanning study demonstrated that the neointimal index in the pioglitazone group was significantly smaller than that in the control group (28% +/- 9% vs 48% +/- 15%, respectively, P <.0001). CONCLUSION: A serial intravascular ultrasound scanning assessment demonstrated that pioglitazone reduces neointimal tissue proliferation after coronary stent implantation in patients with type 2 diabetes mellitus.

Impact of insulin resistance on neointimal tissue proliferation after coronary stent implantation. Intravascular ultrasound studies.

Serial intravascular ultrasound (IVUS) studies in 55 nondiabetic patients showed that neointimal tissue proliferation after stent implantation in patients with impaired glucose tolerance (IGT) was greater than that in patients with normal glucose tolerance at follow-up. Multiple regression analysis showed that the sum of insulin levels was the best predictor of the greater neointimal index at follow-up. Another group of serial IVUS studies were performed in 62 stented lesions in 52 patients with Type 2 diabetes mellitus (DM). The study patients were randomized into a troglitazone group and a control group. The neointimal tissue proliferation at follow-up in the troglitazone group was significantly smaller than that in the control group.

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.

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.

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.

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.

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.

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.