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COZMA, D.,et al.: Mechanism of Atrial Fibrillation: Decremental Conduction, Fragmentation, and Ectopic Activity in Patients with Drug Resistant Paroxysmal Atrial Fibrillation and Structurally Normal Heart. Atrial fibrillation (AF) has been associated with premature beats and decreased atrial conduction velocity. This study examined a new index of dynamic inter-atrial conduction time (iaCT) in patients with paroxysmal AF (PAF). We compared 42 consecutive patients with paroxysmal AF (mean age= 52± 16 years) without structural heart disease with 39 age-matched patients (mean age= 49± 15 years) who underwent ablation of junctional tachycardias. Prior to investigation, all antiarrhythmic drugs were discontinued for an appropriate period of time. The following measurements were made: baseline iaCT (iaCTb) between high right atrium (HRA) and distal coronary sinus, iaCT during HRA pacing S1S1 600 ms (iaCTS1), maximum prolongation of iaCT during S2 and S3 delivery (iaCTS2, iaCTS3). We then derived the decremental index (DI), the maximum percent prolongation of iaCT= iaCT S3-iaCTS1/iaCTS1%. In patients with PAF, iaCTb was 81.3± 24 ms versus 59.5± 14 ms in controls (P= 0.0001). Atrial fibrillation was reproducibly and easily induced with a prominent increase in iaCT in 11 patients with AF. In this subgroup DI was 92± 17%, compared to 45± 21% in the other patients with AF (P= 0.0001) and 21± 15% in the control group (P= 0.0001). Spontaneous isolated or repetitive ectopic activity was observed in 11 patients with AF (26%), and decremental atrial conduction was observed in 76% of patients with AF. This study supports the role of dynamic inter-atrial conduction disturbances in patients with lone PAF. The DI may be a new index of vulnerability to paroxysmal AF.(PACE 2005; 28:S115–S119) [ABSTRACT FROM AUTHOR]

An abstract of the article "Tissue Doppler Imaging: a reliable method for estimation of the left ventricular end-diastolic pressure in patients with chronic heart failure," by C. Mornos and colleagues is presented.

An abstract of the article "A novel index combining diastolic and systolic tissue Doppler parameters: correlation with NTproBNP levels in patients with left ventricular dysfunction," by C. Mornos and colleagues is presented.

An abstract of the article "Lateral, medial or average tissue Doppler velocities for the non-invasive assessment of left ventricular filling pressures in patients with dilated cardiomiopathy?," by C. Morno and colleagues is presented.

An abstract of the article "Left Atrial Volume Index Is an Independent Predictor of NT pro-BNP Level in Patients With Left Ventricular Dysfunction," by S. Miclaus and colleagues is presented.

The article presents an abstract of the study "Tissue Doppler Imaging: A Non-Invasive Technique for Estimation of NT Pro-BNP Levels in Patients with Left Ventricular Dysfunction," by C. Mornos and colleagues.

Objective of the Study: to evaluate the relation between global myocardial index (GMI) and the pattern of left ventricular (LV) volume curves variation, using automatic border detection (ABD), and their role in assessing LV asynchrony. Methods: We studied 52 patients (mean age = 55 ± 17 years) with dilated cardiomyopathy. QRS duration (QRSd) and GMI were measured. Currently accepted TDI and M-mode parameters were used to indicate LV dyssynchrony. On-line continuous LV volume changes were recorded using ABD. Ejection time (ET ABD) was measured from the ABD wave-forms as time interval between maximal and minimal volume variation during LV electromechanical systole. We derived the ejection time index (ETiABD) as the ratio between ET ABD and RR interval (ETiABD = ET/RR). Results: 31 patients had a QRSd >120 ms and 21 patients had a QRSd <120 ms. Ventricular dyssynchrony was observed in 39 patients (29 patients had a QRSd > 120 ms). GMI was significantly higher in patients with, than in patients without ventricular dyssynchrony (1.06 ± 0.18 vs 0.73 ± 0.13, P = 0.0001), while ETABD was significantly smaller (233 ± 39 ms vs 321 ± 28 ms, P = 0.0001). The corresponding difference for ETiABD was 26.9 ± 6.8% vs 6.3 ± 4%, P < 0.0001. By simple regression analysis an inverse linear correlation was observed between GMI and ETiABD (r2=–0.51, P < 0.0001). The pattern of ABD waveforms showed increased isovolumic contraction and relaxation times in patients with LV asynchrony, similar to the GMI pattern. Conclusions: Regional delays in ventricular activation cause uncoordinated and prolonged ventricular contractions, with lengthening of the isovolumic contraction and relaxation times and shortening of the time available for filling and ejection. GMI explores these parameters and together with ABD might be useful to identify patients with ventricular asynchrony. [ABSTRACT FROM AUTHOR]

Background: The ellipse formula often underestimates left atrial (LA) dilation. Complete echocardiographic analysis of LA shape in relation to electrical remodeling has not been performed. Aim of the Study: To analyze the relation between LA shape/surface and vulnerability to atrial fibrillation (AF). Methods: We studied 112 patients aged 43 ± 16 years, and referred for electrophysiological study. LA surface (LAS) was measured at end-systole (maximal). Trapezoidal LA shape was defined if the transverse dimension was less than the basal dimension. Decremental index (DI) was calculated as the maximal percentage prolongation of interatrial conduction time during atrial extrastimulation. The LA was considered vulnerable if AF was inducible. DI >50%, repetitive atrial activity, and fragmented electrograms defined susceptibility to vulnerability. Results: LAS ranged between 10.5 and 36.6 cm2; 77 patients had a trapezoidal LA. By simple regression analysis LAS correlated with DI (r2= 0.38, P = 0.0001). LAS predicted susceptibility to vulnerability better than vulnerability to AF (area under the ROC curve: 0.93 vs 0.81). The best cut-off value for LAS as predictor of susceptibility to vulnerability was 19.5 cm2 (sensitivity: 89%; specificity: 90.5%; positive predictive value: 93.4%; negative predictive value: 84.4%). Using LAS >25 cm2 as a cut-off value, LA vulnerability to AF was detected with a sensitivity of 56.2% and a specificity of 95% (positive predictive value: 81.8%; negative predictive value: 83.3%). LA shape was trapezoidal in 72% patients with LAS >25 cm2 and in 30% patients with LAS <19.5 cm2 (P < 0.0001). Conclusions: LA dilation and electrical remodeling are related. Progressive LA dilation is accompanied by shape remodeling. Appropriate characterization of LA remodeling should therefore include LAS measurement and LA shape assessment. [ABSTRACT FROM AUTHOR]