Yoshinori Yasaka

Dependence of peak oxygen uptake on oxygen transport capacity in chronic heart failure: comparison of graded protocol and fixed protocol

Oxygen transport capacity is the most important determinant of maximum oxygen uptake (V(O2) max) in healthy subjects, however, its role is controversial in patients with chronic heart failure (CHF). The aim of this study was to clarify whether the oxygen transport capacity is an actual determinant of exercise capacity in CHF patients. Thirteen CHF patients underwent two maximum exercise tests, i.e., a graded protocol test and a fixed protocol test, measuring expiratory gases, leg blood flow (LBF), and arterial and venous blood gases. The workload of the fixed protocol was set to exceed the peak workload obtained by the graded protocol. Exercise with the fixed protocol caused significantly larger peak V(O2) compared to the graded protocol (813+/-194 to 971+/-203 ml/min, P<0.001). Peak LBF increased by 17%, while the peak leg arterio-venous oxygen difference increased by 5% from the graded protocol to the fixed protocol. The linear correlation between leg venous partial oxygen pressure and peak V(O2) was more clearly manifested in the fixed protocol (r=0.60, P<0.05) than in the graded protocol (r=0.47, NS). In conclusion, the exercise with graded protocol did not always conduct the upper limit of oxygen demand/supply relationship in CHF patients, whereas, the fixed protocol with a larger workload produced larger peak V(O2) and manifested the mechanism to limit V(O2) by oxygen transport capacity.

Detailed comparison of intra-stent conditions 12 months after implantation of everolimus-eluting stents in patients with ST-segment elevation myocardial infarction or stable angina pectoris.

BACKGROUND The differences in lesion morphology between ST-segment elevation myocardial infarction (STEMI) and stable angina (SAP) significantly influence chronic intra-stent conditions after first-generation drug-eluting stent implantation. The study aimed to compare the intra-stent conditions 12 months after implantation of a second-generation everolimus-eluting stent (EES) in patients with STEMI or SAP. METHODS AND RESULTS We examined the lesion morphology before EES implantation in 53 patients (23 STEMI, 30 SAP) using virtual histology intravascular ultrasound. We maintained dual anti-platelet therapy for 12 months and subsequently analyzed intra-stent conditions using optical coherence tomography and angioscopy. Pre-intervention plaque and necrotic core volume/length, remodeling index, and the incidence of thin-cap fibroatheroma and thrombus were significantly greater in STEMI than in SAP. After 12 months, the median neointimal thickness (117.6 μm vs. 126.0 μm), frequency of uncovered struts (1.2% ± 2.3% vs. 1.0% ± 2.3%), and percentage of stents fully covered with neointima (60.9% vs. 61.1%) were similar between the 2 groups. Meanwhile, the frequency of malapposed struts (0.4% ± 0.6% vs. 0.1% ± 0.4%, p=0.04) and neointimal unevenness score (1.74 ± 0.21 vs. 1.64 ± 0.16, p=0.04) were significantly higher in STEMI than in SAP. The neointimal color grade was more xanthochromatic in STEMI than in SAP. However, the differences were not associated with the incidence of clinical events and intra-stent thrombus (21.7% vs. 16.7%, p=0.89). CONCLUSIONS Although a small degree of delayed healing still persists with second-generation EES, EES promotes a favorable arterial healing response in patients with STEMI, as well as those with SAP.

Impact of esophageal temperature monitoring guided atrial fibrillation ablation on preventing asymptomatic excessive transmural injury

Even with the use of a reduced energy setting (20–25 W), excessive transmural injury (ETI) following catheter ablation of atrial fibrillation (AF) is reported to develop in 10% of patients. However, the incidence of ETI depends on the pulmonary vein isolation (PVI) method and its esophageal temperature monitor setting. Data comparing the incidence of ETI following AF ablation with and without esophageal temperature monitoring (ETM) are still lacking.

Topographic variability of the left atrium and pulmonary veins assessed by 3D-CT predicts the recurrence of atrial fibrillation after catheter ablation☆

Catheter ablation (CA) is an established therapy for atrial fibrillation (AF). However, the assessment of anatomical information and predictors of AF recurrence remain unclear. We investigated the relationship between anatomical information on the left atrium (LA) and pulmonary veins (PVs) from three‐dimensional computed tomography images and the recurrence of AF after CA.

Longitudinal strain combined with delayed-enhancement magnetic resonance improves risk stratification in patients with dilated cardiomyopathy

Objective Late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR) imaging has been reported to be associated with unfavourable outcomes; however, few studies have addressed the prognostic value of left ventricular (LV) deformation parameter indicated by global longitudinal strain (GLS) in two-dimensional speckle-tracking (2DST) echocardiography in patients with non-ischaemic dilated cardiomyopathy (DCM). This study aims to investigate whether the combination of GLS and LGE is useful in stratifying the risk in patients with DCM. Methods We studied 179 consecutive symptomatic patients with DCM (age, 61±15 years; 121 males; left ventricular ejection fraction (LVEF) 33%±9%; New York Heart Association (NYHA) class II: n=71, III: n=107, IV: n=1) who underwent CMR and echocardiography with conventional assessment and 2DST analysis. Results There were 40 rehospitalisations for heart failure, including 7 cardiac deaths and 2 implantations of LV assist device during follow-up (3.8±2.5 years). Univariable Cox proportional hazard regression analysis showed that NYHA class, blood pressure, B-type natriuretic peptide, LV end-diastolic and end-systolic volumes, LVEF, left atrium volume, GLS and LGE were significantly associated with long-term outcome. Multivariable analysis revealed that GLS and LGE were independently associated with long-term outcome (p<0.05, both). In additional analyses, we found independent associations between GLS and LV reverse remodelling after the optimal medical therapy, and between LGE and life-threatening arrhythmias (p<0.05, both). Conclusion Combining GLS and LGE could be useful for risk stratification and prognostic assessment in patients with DCM.

Incidence of esophageal injury after pulmonary vein isolation in patients with a low body mass index and esophageal temperature monitoring at a 39 °C setting

Esophageal injury following catheter ablation of atrial fibrillation (AF) is reported to occur in 35% of patients. Even with a low energy setting (20–25 W), lesions develop in 10% of patients. Body mass index (BMI) has been reported to be a predictor of esophageal injury, indicating that patients with a low BMI (<24.9 kg/m2) are at a higher risk. We hypothesized that catheter ablation with a lower energy setting of 20 W controlled by esophageal temperature monitoring (ETM) at 39 °C could prevent esophageal injury even in patients with a BMI <24.9 kg/m2.

Visualizing radiofrequency lesions using delayed-enhancement magnetic resonance imaging in patients with atrial fibrillation: A modification of the method used by the University of Utah group

Atrial tissue fibrosis has previously been identified using delayed‐enhancement MRI (DE‐MRI) in patients with atrial fibrillation (AF). Although the clinical importance of DE‐MRI is well recognized, the visualization of atrial fibrosis and radiofrequency (RF) lesions has still not been achieved in Japan, primarily because of the differences in contrast agents, volume‐rendering tools, and technical experience. The objective of this study was to visualize RF lesions by using commercially available tools.

Usefulness of non–contrast‐enhanced MRI with two‐dimensional balanced steady‐state free precession for the acquisition of the pulmonary venous and left atrial anatomy pre catheter ablation of atrial fibrillation: Comparison with contrast enhanced CT in clinical cases

To investigate the feasibility of substituting non–contrast‐enhanced MR (non–CE‐MR) imaging with a two‐dimensional (2D) balanced steady‐state free precession (b‐SSFP) sequence for contrast‐enhanced computed tomography (CE‐CT) for atrial fibrillation (AF) ablation.

Acquisition of the pulmonary venous and left atrial anatomy with non-contrast-enhanced MRI for catheter ablation of atrial fibrillation: Usefulness of two-dimensional balanced steady-state free precession

Usually, the pulmonary venous and left atrial (PV–LA) anatomy is assessed with contrast‐enhanced computed tomographic imaging for catheter ablation of atrial fibrillation (AF). A non‐contrast‐enhanced magnetic resonance (MR) imaging method has not been established. Three‐dimensional balanced steady‐state free precession (3D b‐SSFP) sequences cannot visualize the PV–LA anatomy simultaneously because of the signal intensity defect of pulmonary veins. We compared two‐dimensional (2D) b‐SSFP sequences with 3D b‐SSFP sequences in depicting the PV–LA anatomy with non‐contrast‐enhanced MR imaging for AF ablation.

Visualization of the radiofrequency lesion after pulmonary vein isolation using delayed enhancement magnetic resonance imaging fused with magnetic resonance angiography.

The radiofrequency (RF) lesions for atrial fibrillation (AF) ablation can be visualized by delayed enhancement magnetic resonance imaging (DE‐MRI). However, the quality of anatomical information provided by DE‐MRI is not adequate due to its spatial resolution. In contrast, magnetic resonance angiography (MRA) provides similar information regarding the left atrium (LA) and pulmonary veins (PVs) as computed tomography angiography. We hypothesized that DE‐MRI fused with MRA will compensate for the inadequate image quality provided by DE‐MRI.