Katsuhito Yamamoto

Efficacy and safety of rivaroxaban in extreme elderly patients with atrial fibrillation: Analysis of the Shikoku Rivaroxaban Registry Trial (SRRT)

BACKGROUND The Shikoku Rivaroxaban Registry Trial (SRRT) is a retrospective survey of the use of rivaroxaban for stroke prevention in elderly patients in Shikoku, Japan. METHODS The SRRT enrolled 1339 patients from 8 hospitals. Patients were divided into two groups according to their age, the extreme elderly group (453 patients aged ≧80 years) and the control group (886 patients aged <80 years). RESULTS In the extreme elderly group, 41.5% of the patients had low body weight (<50kg) and 65.1% had abnormal renal function (creatinine clearance <50ml/min). The mean CHADS2, CHA2DS2-VASc, and HAS BLED scores were 2.7, 4.4, and 2.3, respectively. There were 333 (73.5%) patients who met the dosing criteria, and of these patients, 81.2% received rivaroxaban 10mg daily. Thromboembolic events occurred in 4 patients (0.94%/person year) and intracranial hemorrhage occurred in 4 patients (0.89%/person year). The incidence of these events was not significantly different from the control group. In addition, all patients with cerebral infarction had been treated with a smaller dose of rivaroxaban than recommended by the dosing criteria, suggesting that dosing criteria should be adhered to. CONCLUSION These results suggest that rivaroxaban is effective and safe in extreme elderly patients with atrial fibrillation.

Effects of Verapamil and Magnesium Sulfate on Electrophysiologic Changes During Acute Myocardial Ischemia and Following Reperfusion in Dogs: Comparative Effects of Administration by Intravenous and Coronary Sinus Retroperfusion Routes

The authors evaluated the effects of verapamil (Ve) and magnesium sulfate (Mg) on the electrophysiologic changes induced in dogs during acute myocardial ischemia and following reperfusion. The effects of their intravenous (IV) administration and adminis tration by coronary sinus retroperfusion (CSR) were also compared. Sixty-five dogs were divided into five groups : Ve-IV: 9 dogs, 0.1 mg/kg; Ve-CS: 9 dogs, 0.05 mg/kg; Mg-IV: 12 dogs, 20 mg/kg; Mg-CS: 11 dogs, 10 mg/kg, control: 24 dogs. The left anterior descending coronary artery was ligated for ten minutes, then quickly reopened. The changes in ventricular effective refractory period (ERP) and intramyocardial conduction time (ICT) were determined during ischemia and following reperfusion. The authors observed a shortening of the ERP and a prolongation of the ICT in the control group versus an attenuation of those effects in all other groups. The ERP was shortened to a lesser extent in the Mg-IV group than in the Ve-IV group. Drug adminis tration by CSR inhibited the changes in ERP and ICT to a greater extent than IV admin istration, even though the dose given by CSR was one-half the IV dose. Ventricular fibril lation (Vf) occurred in 12 of 24 dogs (50%) in the control group during ischemia, and in 5 of 12 dogs (41.7%) following reperfusion. Vf occurred during ischemia and following reperfusion, respectively, in 22.2% and 0% in the Ve-IV and Ve-CS groups, in 25% and 22.2% in the Mg-IV group, and in 9.1% and 10% in the Mg-CS group. Thus, verapamil and magnesium sulfate inhibited the electrophysiologic changes and prevented ventric ular arrhythmias during myocardial ischemia and following reperfusion. Administering the antiarrhythmic agent by coronary sinus retroperfusion may be useful for treating patients with acute myocardial infarction with intractable arrhyth mias, according to these experimental results.

Mechanisms of changes in functional mitral regurgitation by preload alterations

BACKGROUND This study aimed to investigate the mechanisms of acute changes in functional mitral regurgitation (FMR) by preload alterations. METHODS Twenty-two consecutive patients with left ventricular ejection fraction <40% and at least mild FMR underwent transthoracic echocardiography. Passive leg lifting and sublingual administration of nitroglycerin were performed to alter preload. Mitral regurgitant volume (MRV) was assessed using the Doppler method. RESULTS MRV changed in parallel with preload alterations. MRV correlated better with tenting height (TH) than with mitral annular area (MAA) at baseline, whereas the difference in the correlate coefficients was not statistically significant (R=0.69 and R=0.40, respectively; p=0.19). On the other hand, changes in MRV between each sequential stage correlated better with those in MAA than with those in TH (R=0.68 and R=0.44, respectively; p=0.043). Multiple regression analysis revealed that baseline TH was the independent determinant of baseline MRV (R=0.69, p=0.0004), whereas changes in MAA with preload alteration were the independent determinant of the changes in MRV (R=0.68, p<0.0001). Changes in left atrial (LA) volume were the independent determinant of the changes in MAA (R=0.30, p=0.0063). CONCLUSIONS Acute changes in FMR with preload alterations resulted from the transverse changes in MAA rather than the longitudinal changes in tethering-tenting of mitral geometry, and mitral annular deformation was determined by changes in LA volume. Preload reduction might help heart failure treatment through the reduction in FMR resulting from the decrease in LA and mitral annular size.

Early Detection of Abnormal Left Atrial and Left Ventricular Coupling, Using Two-dimensional Speckle Tracking Echocardiography in Patients with Preserved Left Ventricular Ejection Fraction

Aims: The aim of this study was to detect the abnormalities of left atrial (LA)-left ventricular (LV) coupling using two-dimensional speckle tracking echocardiography in patient with preserved LV ejection fraction. Methods: A total of 177 asymptomatic patients with preserved LV ejection fraction were studied. Global LV longitudinal peak strain (GLS) and peak LA longitudinal strain during systole (PALS) were measured. The ratio of E/Ea to PALS was used as an index of LA stiffness. Results: The patients were classified into 2 groups according to the GLS: impaired group (n=81; GLS>-18%) and normal group (n=96; GLS≤-18%). Both GLS and PALS were reduced in the impaired group (p<0.001). LA stiffness was increased in the impaired group (p<0.05). In the normal group, there was no significant correlation between GLS and LA volume index. There was no significant correlation between GLS and LA stiffness. In the impaired group, GLS significantly correlated with correlated with the LA stiffness (r=0.50, p<0.001). Similarly, GLS significantly correlated with LA volume index (r=0.36, p<0.001). Original Research Article Ohara et al.; CA, 5(4): 1-9, 2016; Article no.CA.29072 2 Conclusions: In patients with preserved longitudinal LV systolic function, LA structure and function are preserved. However, LA structure and function are rapidly impaired in patients with reduced longitudinal LV systolic function. LV longitudinal systolic dysfunction may cause the LA wall to become stiffer rapidly.