Grid-mapping catheters versus PentaRay catheters for left atrial mapping on ensite precision mapping system.

INTRODUCTION: Areas displaying reduced bipolar voltage are defined as low-voltage areas (LVAs). Moreover, left atrial (LA) LVAs after pulmonary vein isolation (PVI) have been reported as a predictor of recurrent atrial fibrillation (AF). In this study, we compared grid mapping catheter (GMC) with PentaRay catheter (PC) for LA voltage mapping on Ensite Precision mapping system. METHODS: Twenty-six consecutive patients with LVAs and border zone within the LA were enrolled. After achieving PVI, voltage mapping under high right atrial pacing for 600 ms was performed twice using each catheter type (GMC first, PC next). Furthermore, LVA was defined as a region with a bipolar voltage of <0.50, and border zone was defined as a region with a bipolar voltage of <1.0, or <1.5 mV. RESULTS: Compared with PC, using GMC, voltage mapping contained more mapping points (20 242 [15 859, 26 013] vs. 5589 [4088, 7649]; p < .0001), and more mapping points per minute(1428 [1275, 1803] vs. 558 [372, 783]; p < .0001). In addition, LVA and border zone size using GMC was significantly less than that reported using PC: <1.0 mV (5.9 cm2 [2.9, 20.2] vs. 13.9 cm2 [6.3, 24.1], p = .018) and <1.5 mV voltage cutoff (10.6 cm2 [6.6, 27.2] vs. 21.6 cm2 [12.6, 35.0], p = .005). CONCLUSION: Bipolar voltage amplitude estimated by GMC was significantly larger than that estimated by PC on Ensite Precision mapping system. GMC may be able to find highly selective identification of LVAs with lower prevalence and smaller LVA and border zone size.

Changes in atrial electrophysiological and structural substrate and their relationship to histology in a long-term chronic canine atrial fibrillation model.

BACKGROUND: Atrial fibrillation (AF) is related to numerous electrophysiological changes; however, the extent of structural and electrophysiological remodeling with long-term AF is not well characterized. METHODS: Dogs (n = 6) were implanted with a neurostimulator in the right atrium (AF group). No implantation was done in the Control group (n = 3). Electroanatomical mapping was done prior to and following more than 6 months of AF. Magnetic resonance imaging was also done to assess structural remodeling. Animals were euthanized and tissue samples were acquired for histological analysis. RESULTS: A significant increase was seen in the left atrial (LA) volume among all AF animals (22.25 ± 12.60 cm3 vs 34.00 ± 12.23 cm3 , P = .01). Also, mean bipolar amplitude in the LA significantly decreased from 5.96 ± 2.17 mV at baseline to 3.23 ± 1.51 mV (P < .01) after chronic AF. Those significant changes occurred in each anterior, lateral, posterior, septal, and roof regions as well. Additionally, the dominant frequency (DF) in the LA increased from 7.02 ± 0.37 Hz to 10.12 ± 0.28 Hz at chronic AF (P < .01). Moreover, the percentage of fibrosis in chronic AF animals was significantly larger than that of control animals in each location (P < .01). CONCLUSIONS: Canine chronic AF is accompanied by a significant decrease in intracardiac bipolar amplitudes. These decreased electrogram amplitude values are still higher than traditional cut-off values used for diseased myocardial tissue. Despite these "normal" bipolar amplitudes, there is a significant increase in DF and tissue fibrosis.

The association between high-dose loop diuretic use at discharge and cardiovascular mortality in patients with heart failure.

AIMS: Few studies have reported the impact of high-dose loop diuretics at discharge on prognosis in Japanese patients with heart failure (HF). Our purpose was to assess the relationship between the dose of loop diuretics at discharge and cardiovascular mortality in patients with HF. METHODS AND RESULTS: We enrolled decompensated HF patients who were admitted to our hospital between March 2010 and March 2015, and compared HF patients who received high-dose loop diuretics at discharge (HD group) with low-dose loop diuretics at discharge (LD group) with regard to risk of cardiovascular mortality, and all-cause mortality. High-dose loop diuretic was defined as ≥40 mg/day of oral furosemide at discharge. A total of 215 patients were enrolled to the study. The median follow-up duration was 641 days. All-cause and cardiovascular mortality were significantly lower in the LD group than in the HD group (10.4% vs. 31.6%, P < 0.001; 2.2% vs. 24.6%, P < 0.001, respectively). High-dose loop diuretics were associated with cardiovascular mortality in multivariate Cox proportional hazards model (hazard ratio, 16.06, 95% confidence interval 3.457 to 116.8; P < 0.001). The largest area under the receiver operating characteristic curve (0.85) for cardiovascular death was obtained with a threshold of 40 mg furosemide. CONCLUSIONS: High-dose loop diuretic use at discharge was one of the predictors of cardiovascular mortality in patients with HF. An oral furosemide dose of 40 mg daily may be defined as 'high-dose' loop diuretics in Japanese patients with chronic HF.

Importance of nonpulmonary vein foci in catheter ablation for paroxysmal atrial fibrillation.

BACKGROUND: Pulmonary vein (PV) isolation is an established treatment strategy for paroxysmal atrial fibrillation (PAF). However, the recurrence rate of PAF is 8% to 37%, despite repeated procedures, and the catheter ablation strategy for PAF with non-PV foci is unclear. OBJECTIVE: The purpose of this study was to assess the PAF ablation strategy for non-PV foci. METHODS: The study included 304 consecutive patients undergoing PAF ablation (209 males, age 63.0 ± 10.4 years) divided into 3 groups: group 1 (245 patients) with no inducible non-PV foci; group 2 (34 patients) with atrial fibrillation (AF) originating from non-PV foci and all the foci successfully ablated; and group 3 (25 patients) with AF originating from non-PV triggers, but without all foci being ablated or with persistently inducible AF. RESULTS: Mean follow-up period was 26.9 ± 11.8 months, and AF recurrence rates since the last procedure were 9.8%, 8.8%, and 68.0% in groups 1, 2, and 3, respectively. There was no statistically significant difference in recurrence rate between groups 1 and 2 (P = .89); however, there were statistically significant differences between groups 3 and 1 (P <.0001) and groups 3 and 2 (P <.0001). The patients in group 2 had an AF-free outcome to equivalent to those who had PV foci in group 1 (P = .83). CONCLUSION: Success rates can be improved for PAF ablation if non-PV foci are detected and eliminated.