Ability of Left Atrial Distensibility After Radiofrequency Catheter Ablation to Predict Recurrence of Atrial Fibrillation.

This study sought to assess the left atrial (LA) functional recovery after radiofrequency catheter ablation (RFCA) for atrial fibrillation (AF) and to evaluate the determining factor of procedural success of RFCA, using a novel preload stress echocardiography. A total of 111 patients with AF were prospectively recruited. The echocardiographic parameters were obtained during the leg-positive pressure (LPP) maneuver, both at baseline and midterm after RFCA. As an index of LA distensibility, the LA expansion index was calculated as (LAVmax - LAVmin) × 100 / LAVmin. During a median follow-up period of 14.2 months, AF recurrence was observed in 23 patients (20.7%). In LA functional parameters at baseline, only the Δ LA expansion index was significantly larger in the success group (16 ± 11% vs 4 ± 9%, p <0.05). At midterm follow-up, the Δ LA expansion index significantly increased to 32 ± 19% (p <0.05), together with structural LA reverse remodeling only in the success group. Moreover, the Δ stroke volume index during the LPP stress test significantly increased only in the success group (from 2.3 ± 1.3 ml/m2 to 3.1 ± 4.8 ml/m2, p <0.05). In a multivariate analysis, left ventricular ejection fraction (hazard ratio 0.911, p <0.05) and baseline Δ LA expansion index (hazard ratio 0.827, p <0.001) were independent predictors of AF recurrence. In conclusion, the baseline Δ LA expansion index during LPP stress is a reliable marker for predicting procedural success after RFCA. Moreover, maintenance of sinus rhythm resulted in an improvement of the preload reserve after RFCA.

Effects of Radiofrequency Catheter Ablation on Cardiac Reserve Using Preload Stress Echocardiography in Paroxysmal and Persistent Atrial Fibrillation.

The effects of catheter ablation on exercise tolerance and quality of life in patients with atrial fibrillation (AF) have been reported. We assessed cardiac function in more detail using the leg positive pressure (LPP) technique and found that contractile reserve is particularly important in relation to exercise tolerance and prognosis. In this study, we used the LPP technique to examine changes in contractile reserve immediately after ablation and 6 months later. We prospectively enrolled patients who underwent catheter ablation for AF at 2 institutes. We performed LPP stress echocardiography 2 to 3 days after (FU-1) and 6 months after (FU-2) ablation to examine changes in cardiac function indexes. The primary end point was improvement in contractile reserve. Ultimately, 109 patients (mean age 67.4 ± 9.6 years; 70% men) underwent 2 sessions of LPP stress echocardiography. The median CHA2DS2-VASC score was 2 (interquartile range 13). From FU-1 to FU-2, the change in the stroke volume index after the LPP maneuver increased in patients with paroxysmal and persistent AF with low CHA2DS2-VASC scores (both p <0.05). Regardless of AF subtype, contractile reserve at FU-2 improved in patients with low CHA2DS2-VASC scores compared with that at FU-1. In contrast, patients with high CHA2DS2-VASC scores had no change. In conclusion, patients with AF with a low CHA2DS2-VASC score had improved contractile reserve after ablation, whereas patients with high scores did not show any improvement. Aggressive interventions in patients with high scores may lead to better management after catheter ablation.

Relationship between coronary flow reserve evaluated by phase-contrast cine cardiovascular magnetic resonance and serum eicosapentaenoic acid.

BACKGROUND: Long-term intake of long-chain n-3 polyunsaturated fatty acids (n-3 PUFAs), especially eicosapentaenoic acid (EPA) is associated with a low risk for cardiovascular disease. Phase-contrast cine cardiovascular magnetic resonance (PC cine CMR) can assess coronary flow reserve (CFR). The present study investigates the relationship between CFR evaluated by PC cine CMR and the serum EPA. METHODS: We studied 127 patients (male, 116 (91%); mean age, 72.2 ± 7.4 years) with known or suspected coronary artery disease (CAD). X-ray coronary angiography revealed no significant coronary arterial stenoses (defined as luminal diameter reduction ≥ 50% on quantitative coronary angiogram (QCA) analysis) in all study participants. Breath-hold PC cine CMR images of the coronary sinus (CS) were acquired to assess blood flow of the CS both at rest and during adenosine triphosphate (ATP) infusion. We calculated CFR as CS blood flow during ATP infusion divided by that at rest. Patients were allocated to groups according to whether they had high (n = 64, EPA ≥ 75.8 µg/mL) or low (n = 63, EPA < 75.8 µg/mL) median serum EPA. RESULTS: CFR was significantly lower in the low, than in the high EPA group (2.54 ± 1.00 vs. 2.91 ± 0.98, p = 0.038). Serum EPA positively correlated with CFR (R = 0.35, p < 0.001). We defined preserved CFR as > 2.5, which is the previously reported lower limit of normal flow reserve without obstructive CAD. Multivariate analysis revealed that EPA is an independent predictor of CFR > 2.5 (odds ratio, 1.01; 95% confidence interval, 1.00 - 1.02, p = 0.008). CONCLUSIONS: The serum EPA is significantly correlated with CFR in CAD patients without significant coronary artery stenosis.

A role of the -35 element in the initiation of transcription at psbA promoter in tobacco plastids.

Most plastid promoters recognized by bacteria-like plastid RNA polymerase (PEP) are similar to E. coli sigma(70)-type promoters comprising "-35" and "-10" elements. Among them, psbA promoter is unique in bearing additional elements between the conserved -35 and -10 elements. The psbA promoter activity is differentially maintained in the mature chloroplasts where the activity of most PEP promoters declines. Previously, we identified two types of PEP activities in wheat seedlings [Satoh et al. (1999) Plant J. 18: 407]; PEP present in the mature chloroplasts of the leaf tip (tip-type PEP) can initiate transcription from the -35-destructed psbA promoter, but the -35 element is essential for transcription by PEP present in immature chloroplasts of the leaf base (base-type PEP). To reveal which type of PEP functions in various types of plastids in tobacco, we analyzed the tobacco psbA promoter by means of a transplastomic approach. The promoter core context (-42 to +9) was sufficient for developmental regulation of the psbA promoter activity. The -35 promoter element was important for transcription initiation at the psbA promoter in all types of plastids, including chloroplasts in mature leaves, leucoplasts in roots, etioplasts in etiolated cotyledons. The conclusion is that the PEP bearing a promoter preference, similar to the wheat base-type PEP, functions dominantly in tobacco chloroplasts.