Yuko Hatakeyama

Prognostic Significance of Frequent Premature Ventricular Contractions Originating from the Ventricular Outflow Tract in Patients with Normal Left Ventricular Function.

Background: Recently, it has been reported that frequent premature ventricular contractions (PVCs) may be associated with causing heart failure in patients with left ventricular (LV) dysfunction. However, the prognostic significance of frequent PVCs in asymptomatic patients with a normal LV function is unclear. Methods: Two hundred and thirty-nine consecutive patients presenting with frequent PVCs (>1000 beats/day) originating from the right or left ventricular outflow tract without any detectable heart disease were enrolled in the study. Structural heart disease was ruled out by echocardiography and cardiac magnetic resonance imaging, and Holter-ECG monitoring was repeated two or three times to evaluate the PVC prevalence at the initial evaluation. All patients were followed up for at least 4 years, and further observation was continued if possible. Results: During an observation period of 5.6 (1.7) years, no patients exhibited any serious cardiac events. Although there was no significant change in the mean LV ejection fraction (LVEF) and mean LV diastolic dimension (LVDd), there was a significant negative correlation between the PVC prevalence and ΔLVEF (p<0.001) and positive correlation between the PVC prevalence and ΔLVDd (p<0.001). When the development of LV dysfunction was defined as ΔLVEF>−6%, 13 patients exhibited LV dysfunction. For the prediction of the development of LV dysfunction, PVC prevalence and LVEF at the initial evaluation were independent predicting factors (p<0.01). Conclusion: Although the prognosis in patients with frequent PVCs was considered relatively benign, attention should be paid to the progression of the LV dysfunction during a long-term observation, especially in patients with a high PVC prevalence.

Postprandial hyperglycemia and endothelial function in type 2 diabetes: focus on mitiglinide

The risk of cardiovascular complication in a diabetes patient is similar to that in a nondiabetic patient with a history of myocardial infarction. Although intensive control of glycemia achieved by conventional antidiabetic agents decreases microvascular complications such as retinopathy and nephropathy, no marked effect has been reported on macrovascular complications or all-cause mortality. Evidence from VADT, ACCORD, and ADVANCE would suggest that glycemic control has little effect on macrovascular outcomes. Moreover, in the case of ACCORD, intensive glycemic control may be associated with an increased risk of mortality. There is sufficient evidence that suggests that postprandial hyperglycemia may be an independent risk factor for cardiovascular disease in diabetes patients. However, there are no prospective clinical trials supporting the recommendation that lowering postprandial blood glucose leads to lower risk of cardiovascular outcomes. Mitiglinide is a short-acting insulinotropic agent used in type 2 diabetes treatment. It has a rapid stimulatory effect on insulin secretion and reduces postprandial plasma glucose level in patients with type 2 diabetes. Because of its short action time, it is unlikely to exert adverse effects related to hypoglycemia early in the morning and between meals. Mitiglinide reduces excess oxidative stress and inflammation, plays a cardioprotective role, and improves postprandial metabolic disorders. Moreover, mitiglinide add-on therapy with pioglitazone favorably affects the vascular endothelial function in type 2 diabetes patients. These data suggest that mitiglinide plays a potentially beneficial role in the improvement of postprandial hyperglycemia in type 2 diabetes patients and can be used to prevent cardiovascular diseases. Although the results of long-term, randomized, placebo-controlled trials for determining the cardiovascular effects of mitiglinide on clinical outcomes are awaited, this review is aimed at summarizing substantial insights into this topic.

Successful Catheter Ablation of Mitral Isthmus Related Multiple and Unstable Ventricular Tachycardias after Myocardial Infarction

Catheter ablation in patients with multiple and unstable postinfarction ventricular tachycardias (VTs) by placing lines of radiofrequency lesions with using 3D electroanatomical mapping is still challenging. We report a case of 69-years-old male with such VTs in which a linear lesion across the mitral isthmus successfully eliminated tachycardias. Four distinct unstable VTs were induced: three with a left bundle (LB) and one with a right bundle (RB) morphology. The analysis of the ventricular activation sequence along the posterior aspect of the mitral annulus (coronary sinus) revealed that the direction of wavefront propagation during the LB-VTs was opposite to that during the RB-VT. Electroanatonical mapping demonstrated a wide inferior infarct region. Then pace mapping was performed along the infarct border to assume the putative exit sites of the induced VTs. Each pacemaps performed along the septal and lateral aspects of the infarct border reproduced the QRS morphology of LB- and RB-VT, respectively. Based on these data, all four VTs were considered to be “mitral isthmus related”. Placement of a linear lesion across the isthmus rendered all VTs noninducible. Mitral isthmus plays a role in the genesis of unstable VT. Even when treating patients with multiple and unstable postinfarction VTs, catheter ablation can be feasible if a critical isthmus is identified in the mitral isthmus.