Yasushi Tatematsu

The incidence and clinical significance of non-isolation of the pulmonary vein carina after encircling ipsilateral pulmonary veins isolation for paroxysmal atrial fibrillation: a pitfall of the double-Lasso technique

AIMS Encircling ipsilateral pulmonary veins (PVs) isolation (EIPVsI) with the double-Lasso technique has proven to be effective to cure atrial fibrillation (AF). However, in this technique, PV mapping with circular catheters may miss a non-isolation of the PV carina. The purpose of this study was to reveal the incidence and clinical significance of a non-isolation of the PV carina after EIPVsI. METHODS AND RESULTS We studied 81 consecutive paroxysmal AF patients (age 61 ± 12 years, 56 men), in whom EIPVsI was successfully performed in one encircling line with the endpoint of the demonstration of bidirectional conduction block between the PVs and left atrium (LA) with the double-Lasso technique. After a successful EIPVsI, pacing from the PV carina was performed and it captured the LA in 17 (21.0%) patients. During a mean follow-up period of 19 ± 13 months, AF recurred in 13 (16.0%) patients. A multivariate Cox proportional analysis revealed that a non-isolation of the PV carina after the EIPVsI was a significant predictor (hazard ratio = 3.91, 95% confidence interval = 1.13-14.16, P = 0.03) of AF recurrence. CONCLUSIONS Pulmonary vein mapping with the double-Lasso technique did miss the non-isolation of the PV carina after a successful EIPVsI, which was an independent predictor of AF recurrence after the EIPVsI. Pacing from the PV carina may be required to confirm the electrical isolation of the PV carina after EIPVsI with the double-Lasso technique.

Demonstration of reversible complete left bundle branch block following tachycardia-induced cardiomyopathy

A 56-year-old man with atrial fibrillation and complete left bundle branch block (CLBBB) developed heart failure refractory to the initial medical treatment. Both the CLBBB and cardiac dysfunction completely recovered only with an advanced medical regimen for rate control and heart failure. This report describes a case with reversible CLBBB following tachycardia-induced cardiomyopathy, who was not a candidate for cardiac resynchronization therapy.

Renin–angiotensin system inhibitors can suppress atrial fibrillation recurrence after encircling ipsilateral pulmonary vein isolation in patients with a non-dilated left atrium

Introduction: The purpose of this study was to investigate whether the effects of renin–angiotensin system inhibitors (RASIs) after encircling ipsilateral pulmonary veins isolation (EIPVsI) for atrial fibrillation (AF) differed between patients with non-dilated and dilated left atria. Materials and methods: We retrospectively studied 292 consecutive patients (mean age=61±11 years, 75% males) who underwent successful EIPVsI for paroxysmal or persistent AF. RASIs’ effects were compared between the patients with a non-dilated left atrium of <40 mm (n=178) and dilated left atrium of ≥40 mm (n=114). Results: During a mean follow-up period of 18.9±12.7 months, AF recurred in 38 (21.4%) and 45 (39.5%) patients with non-dilated and dilated left atria, respectively. A multivariate Cox proportional analysis revealed that treatment with RASIs (hazard ratio (HR) 0.30, 95% confidence interval (CI) =0.13–0.66, p=0.003), the duration of AF (HR 1.08/year, 95% CI=1.01–1.16, p=0.03), a history of hypertension (HR 2.86, 95% CI=1.21–6.85, p=0.02) and the left ventricular ejection fraction (HR 0.54/10%↑, 95% CI=0.34–0.87, p=0.01) were associated with AF recurrences in patients with a non-dilated left atrium. On the other hand, only the duration of AF (HR 1.11/year, 95% CI=1.01–1.21, p=0.03) was associated with AF recurrences in those with a dilated LA, and RASIs had no effect on AF recurrences (p=0.65). Conclusions: RASIs suppressed AF recurrences after EIPVsI only in patients with a non-dilated left atrium.

Imipramine inhibition of TRPM‐like plasmalemmal Mg2+ transport in vascular smooth muscle cells

Depression is associated with vascular disease, such as myocardial infarction and stroke. Pharmacological treatments may contribute to this association. On the other hand, Mg2+ deficiency is also known to be a risk factor for the same category of diseases. In the present study, we examined the effect of imipramine on Mg2+ homeostasis in vascular smooth muscle, especially via melastatin‐type transient receptor potential (TRPM)‐like Mg2+‐permeable channels. The intracellular free Mg2+ concentration ([Mg2+]i) was measured using 31P‐nuclear magnetic resonance (NMR) in porcine carotid arteries that express both TRPM6 and TRPM7, the latter being predominant. pHi and intracellular phosphorus compounds were simultaneously monitored. To rule out Na+‐dependent Mg2+ transport, and to facilitate the activity of Mg2+‐permeable channels, experiments were carried out in the absence of Na+ and Ca2+. Changing the extracellular Mg2+ concentration to 0 and 6 mM significantly decreased and increased [Mg2+]i, respectively, in a time‐dependent manner. Imipramine statistically significantly attenuated both of the bi‐directional [Mg2+]i changes under the Na+‐ and Ca2+‐free conditions. This inhibitory effect was comparable in influx, and much more potent in efflux to that of 2‐aminoethoxydiphenyl borate, a well‐known blocker of TRPM7, a channel that plays a major role in cellular Mg2+ homeostasis. Neither [ATP]i nor pHi correlated with changes in [Mg2+]i. The results indicate that imipramine suppresses Mg2+‐permeable channels presumably through a direct effect on the channel domain. This inhibitory effect appears to contribute, at least partially, to the link between antidepressants and the risk of vascular diseases.

THE PREVALENCE AND CLINICAL SIGNIFICANCE OF CARINA-LA CONDUCTION AFTER SUCCESSFUL PULMONARY VEIN ISOLATION FOR ATRIAL FIBRILLATION

Background: Bidirectional block between pulmonary veins (PVs) and left atrium (LA) is the gold standard to confirm the successful procedure of pulmonary vein isolation (PVI) for atrial fibrillation (AF). However, conduction between carina and LA remains in some cases after PVI, and its clinical significance has remained unclear. The purpose of this study is to clarify the incidence and clinical significance of carina-LA conduction after PVI.