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Atrial Remodeling in Human Hypertension Introduction: Hypertension (HT) is the most common modifiable risk factor for atrial fibrillation (AF), yet little is known of the atrial effects of chronic HT in humans. We aimed to characterize the electrophysiologic (EP) and electroanatomic (EA) remodeling of the right atrium (RA) in patients with chronically treated systemic HT and left ventricular hypertrophy (LVH) without a history of AF. Methods and Results: Twenty patients with (systolic BP 145 ± 10 mmHg) and without (BP 119 ± 11 mmHg, P < 0.01) systemic HT underwent detailed conventional EP and EA voltage and activation mapping. We measured RA refractoriness at the coronary sinus and high septum at cycle lengths (CLs) 600 and 450 ms, and RA conduction velocities, activation times, and voltages at a global and regional level at CLs 600 ms and 300 ms. HT was associated with slowing of global (73 ± 17 cm/s vs 96 ± 12 cm/s in controls, P < 0.01) and regional conduction velocity particularly in the posterior RA (70 ± 17 cm/s vs 96 ± 12 cm/s in controls, P < 0.01) at the crista terminalis (fractionation and double potentials in HT 72%± 4 vs 43%± 23 in controls, P = 0.04). Mean RA voltage was similar between the 2 groups, however HT was associated with an increase in areas of low voltage (<0.5 mV; HT 13% vs controls 9%, P = 0.04). Sustained AF was induced in 30% HT patients and no controls. Conclusion: Chronically treated systemic HT with LVH is accompanied by atrial remodeling characterized by: (i) global conduction slowing, (ii) regional conduction delay particularly at the crista terminalis, and (iii) increased AF inducibility. These changes may in part be responsible for the increased propensity to AF associated with systemic HT. (J Cardiovasc Electrophysiol, Vol. 22, pp. 1317-1324, December 2011) [ABSTRACT FROM AUTHOR]

Catheter-Tissue Contact Force Determines Atrial Electrogram Characteristics Introduction Electrogram (EGM) characteristics are used to infer catheter-tissue contact. We examined if (a) atrial EGM characteristics predicted CF and (b) compared the value of CF versus other surrogates for predicting lesion efficacy. Methods and Results Twelve paroxysmal AF patients underwent pulmonary vein isolation using radiofrequency (RF) ablation facilitated by a novel CF-sensing catheter. Operators were blinded to CF. EGM amplitude, width, and morphology were measured pre- and post-RF. At each RF site, average CF, force-time integral (FTI), impedance fall, time to impedance plateau, maximum power, catheter tip temperature, and total energy delivered were recorded. An effective lesion was defined based on previously validated EGM criteria for transmural lesions. There was a moderate correlation between CF and EGM amplitude (r = 0.19) and EGM width (r = −0.22). Pre-RF, EGM amplitude, and width had modest to poor discriminative capacity for identifying preablation CF (e.g., EGM amplitude identified CF>20 g with sensitivity and specificity of 67% and 60%, respectively). Preablation CF, FTI, and total energy delivered during RF were the only independent predictors of effective lesion formation. Neither pre-RF EGM amplitude/width nor power, temperature, and impedance changes during RF predicted effective lesion formation. An average CF >16 g or FTI >404 g*s had excellent sensitivity and specificity (>80%) for identifying an effective lesion. Conclusions EGM characteristics do not reliably predict either CF before the onset of RF, nor do they predict the likelihood of an effective lesion. CF parameters were superior to power, temperature, and impedance changes during RF in predicting lesion efficacy. [ABSTRACT FROM AUTHOR]

Atrial Remodeling in Pulmonary Hypertension. Introduction: Pulmonary hypertension (PH) is common to a range of cardiopulmonary conditions and is associated with atrial arrhythmias. However, little is known of the isolated atrial effects of PH and right atrial dilatation (RA) in humans. To avoid the confounding effects of PH-associated disease states, we performed detailed electrophysiological (EP) and electroanatomic (EA) mapping of the RA in patients with idiopathic PH. Methods and Results: Eight PH patients (mean pulmonary arterial [PA] pressure 39.0 ± 15.8 mmHg) and 16 age-matched controls (mean PA pressure 11.5 ± 4.1 mmHg, P < 0.0001) were studied. Corrected sinus node recovery times (cSNRT), atrial effective refractory periods (ERPs), conduction delay at the crista terminalis (CT), and inducibility of atrial fibrillation (AF) were evaluated. EA mapping (pacing cycle length 600 and 300 milliseconds) was performed to determine RA global and regional voltage, conduction velocities, atrial activation times, fractionated electrograms and double potentials. Patients with PH demonstrated a prolongation in cSNRT without significant change in atrial ERP and an increase in AF inducibility. PH was associated with lower tissue voltage (1.8 ± 0.4 mV in PH vs 2.2 ± 0.4 mV in controls, P = 0.02), increased low voltage areas (13.7 ± 8.2% in PH vs 6.2 ± 3.7% in controls, P < 0.01) and the presence of electrically silent areas. Conduction velocities were slower (global 67.3 ± 5.6 cm/s vs 92.8 ± 4.0 cm/s, P < 0.001) and fractionated electrograms and double potentials were more prevalent (14.7 ± 4.4% vs 6.3 ± 4.1, P < 0.01) in PH compared with controls, respectively. Conclusion: Idiopathic PH is associated with RA remodeling characterized by: generalized conduction slowing with marked regional abnormalities; reduced tissue voltage; and regions of electrical silence. These changes provide important insights into the isolated effects of PH fundamental to a range of clinical conditions associated with AF. (J Cardiovasc Electrophysiol, Vol. 23, pp. 614-620, June 2012) [ABSTRACT FROM AUTHOR]

Atrial Remodeling in Atrial Fibrillation. Introduction: The nature of the atrial substrate thought to contribute toward maintaining atrial fibrillation (AF) outside the pulmonary veins remains poorly defined. Therefore, our objective was to determine whether patients with paroxysmal and persistent AF have an abnormal electroanatomic substrate within the left atrium (LA). Methods and Results: Thirty-one patients with AF (17 paroxysmal AF and 14 persistent AF) were compared with 15 age-matched controls with left-sided supraventricular tachycardia (SVT). High-density 3-dimensional electroanatomic maps were created and the LA was divided into 8 segments for regional analysis. Bipolar voltage, conduction, and effective refractory periods (ERPs) of the posterior LA, left atrial appendage (LAA), and distal coronary sinus (CSd) and percentage complex signals were assessed. In the majority of LA regions, compared with controls, AF patients had: (1) lower mean voltage and a higher percentage low voltage; (2) slower conduction; and (3) more prevalent complex signals. Many of these changes were more marked in the persistent than the paroxysmal AF group. Conclusions: Patients with AF have lower regional voltage, increased proportion of low voltage, slowed conduction, and increased proportion of complex signals compared to controls. Many of these changes are more pronounced in persistent AF patients, suggesting there may be a progressive nature to the changes. Differences occurred in the absence of structural heart disease. These substrate abnormalities provide further insight into the progressive nature of atrial remodeling and the mechanisms involved in maintenance of AF. (J Cardiovasc Electrophysiol, Vol. 23 p. 232-238, March 2012.) [ABSTRACT FROM AUTHOR]

Objectives: The purpose of this study was to characterize the pattern of atrial remodeling seen with human aging.Background: Atrial fibrillation (AF) occurs in 3% to 4% of the population over 65 years of age. It is associated with thromboembolic complications, worsening heart failure, and increased mortality, yet the electrical and structural remodeling that occurs with human aging remains unknown.Methods: Thirteen patients (66.4 ± 1.7 years) ≥60 years (group A), 13 patients (50 ± 2.1 years) age 31 to 59 years (group B), and 15 patients (24.7 ± 1.0 years) ≤30 years (group C) underwent conventional electrophysiologic studies and electroanatomic mapping. We measured atrial refractoriness (ERP) at the distal coronary sinus (CS); low and high lateral right atrium (LRA) and the high septal right atrium at 600, 500, and 400 ms; maximum corrected sinus node recovery time (CSNRT); P-wave duration (PWD); conduction time (CT) along the CS and LRA; and discrete double potentials (DP) along the crista.Results: Aging was associated with an increase in atrial ERP, prolonged CT along the CS, increased PWD and CSNRT. There was no significant change in dispersion of refractoriness or rate adaptation. Electroanatomic mapping revealed diffuse areas of low voltage with regional conduction slowing. Both techniques demonstrated a greater number of DPs and fractionated signals along the crista terminalis with aging.Conclusions: Aging is associated with regional conduction slowing, anatomically determined conduction delay at the crista, and structural changes that include areas of low voltage. In addition, impairment of sinus node function and an increase in atrial ERP occurred with aging. This electrical and structural remodeling may explain the increased propensity to AF with aging. [Copyright &y& Elsevier]