Cardiac resynchronization therapy (CRT) device replacement considerations: upgrade or downgrade? A complex decision in the current clinical setting.

There are limited data about the management of patients presenting for elective generator replacements in the setting of previously implanted cardiac resynchronization therapy (CRT) devices that are nearing end-of-life. The individual patient's clinical status and concomitant morbidities may evolve so that considerations may include not only replacement of the pulse generator, but also potentially changing the type of device [e.g.

Obstructive sleep apnea syndrome and cardiovascular disease: The influence of C-reactive protein.

Obstructive sleep apnea syndrome (OSAS) is a common medical condition, associated with atherosclerosis and cardiovascular disease (CVD). The underlying pathophysiologic mechanisms of this association have not been completely understood and may be multifactorial in origin. A number of studies suggest that inflammatory processes have emerged critical in the pathogenesis of CVD in OSAS.

Electrophysiological and Electroanatomical Mapping of the Right Atrium in Persistent Atrial Fibrillation: Relation to Collagen Turnover.

Background: Atrial fibrillation (AF) is associated with abnormal atrial substrate. We investigated whether patients with persistent lone AF and patients with persistent AF and nonischemic dilated cardiomyopathy (NIDCM) exhibit any differences in electrophysiological and electroanatomical properties of right atrium (RA) and collagen turnover. We also investigated the relationship between mean RA bipolar voltage and collagen turnover.

Obesity and atrial fibrillation: A comprehensive review of the pathophysiological mechanisms and links.

Obesity is a worldwide health problem with epidemic proportions that has been associated with atrial fibrillation (AF). Even though the underlying pathophysiological mechanisms have not been completely elucidated, several experimental and clinical studies implicate obesity in the initiation and perpetuation of AF. Of note, hypertension, diabetes mellitus, metabolic syndrome, coronary artery disease, and obstructive sleep apnea, represent clinical correlates between obesity and AF.

Diabetes mellitus and atrial fibrillation: Pathophysiological mechanisms and potential upstream therapies.

Diabetes mellitus (DM) represents one of the most important risk factors for atrial fibrillation (AF) while AF is a strong and independent marker of overall mortality and cardiovascular morbidity in diabetic patients. Autonomic, electrical, electromechanical, and structural remodeling, including oxidative stress, connexin remodeling and glycemic fluctuations seem to be implicated in AF pathophysiology in the setting of DM. The present review highlights the association between DM and AF, provides a comprehensive overview of the responsible pathophysiological mechanisms and briefly discusses potential upstream therapies for DM-related atrial remodeling.

Sinus rhythm restoration affects collagen turnover in patients with persistent atrial fibrillation.

Aims: Collagen turnover and atrial fibrosis have been implicated in the generation and perpetuation of atrial fibrillation (AF). We evaluated the importance of serum markers of collagen turnover in predicting the outcome of electrical cardioversion (CV) of persistent AF and the relationship between AF and fibrosis.

Methods And Results: Serum C-terminal pro-peptide of collagen type-I (CICP) and C-terminal telopeptide of collagen type-I (CITP) were measured in 164 patients with AF before and 2 months after CV.

Atrial fibrillation: a progressive atrial myopathy or a distinct disease?

Atrial fibrillation is a complex arrhythmia with multiple possible mechanisms. A lot of experimental and clinical studies have shed light on the pathophysiological mechanisms of arrhythmia, especially on molecular basis. Electrical, contractile and structural remodeling, calcium handling abnormalities, autonomic imbalance and genetic factors seem to play a crucial role in atrial fibrillation initiation and maintenance.

Impact of Atrial Fibrillation on Coronary Blood Flow: A Systematic Review.

Patients with atrial fibrillation (AF) frequently present with symptoms suggestive of myocardial isch- aemia, even in the absence of significant CAD, that seem to be attributable to abnormalities of myocardial perfusion and perfusion reserve. According to the results of recent human and previous experimen- tal studies the increase in coronary artery blood flow during AF is smaller, while the coronary vascular resistance during the arrhythmia does not decrease as much as we would expect, suggesting a mismatch between coronary blood flow and myocardial metabolic demand. AF itself diminishes coronary flow reserve, especially in the subendocardial layer, partly as a result of the increase in the myocardial com- ponent of coronary vascular resistance, and it is possible that irregular ventricular rhythm may play an important role.

Mechanisms, risk factors, and management of acquired long QT syndrome: a comprehensive review.

Long QT syndrome is characterized by prolongation of the corrected QT (QTc) interval on the surface electrocardiogram and is associated with precipitation of torsade de pointes (TdP), a polymorphic ventricular tachycardia that may cause sudden death. Acquired long QT syndrome describes pathologic excessive prolongation of the QT interval, upon exposure to an environmental stressor, with reversion back to normal following removal of the stressor. The most common environmental stressor in acquired long QT syndrome is drug therapy.

Sleep disordered breathing in patients with acute coronary syndromes.

Study Objectives: Although the prevalence of obstructive sleep apnea/hypopnea syndrome (OSAHS) is high in patients with acute coronary syndromes (ACS), there is little knowledge about the persistence of OSAHS in ACS patients after the acute event. We aimed to assess the prevalence and time course of OSAHS in patients with ACS during and after the acute cardiac event.

Methods: Fifty-two patients with first-ever ACS, underwent attended overnight polysomnography (PSG) in our sleep center on the third day after the acute event.

Extracellular matrix alterations in the atria: insights into the mechanisms and perpetuation of atrial fibrillation.

Atrial fibrillation is the most common arrhythmia in clinical practice and is associated with increased cardiovascular morbidity and mortality. Atrial fibrosis, a detrimental process that causes imbalance in extracellular matrix deposition and degradation, has been implicated as a substrate for atrial fibrillation, but the precise mechanisms of structural remodelling and the relationship between atrial fibrosis and atrial fibrillation are not completely understood. A large number of experimental and clinical studies have shed light on the mechanisms of atrial fibrosis at the molecular and cellular level, including interactions between matrix metalloproteinases and their endogenous tissue inhibitors, and profibrotic signals through specific molecules and mediators such as angiotensin II, transforming growth factor-β1, connective tissue growth factor, and platelet-derived growth factor.

Serum markers of collagen turnover predict future shocks in implantable cardioverter-defibrillator recipients with dilated cardiomyopathy on optimal treatment.

Objectives: We investigated prospectively whether serum markers of collagen turnover could be used as predictors for the occurrence of malignant ventricular arrhythmias in patients with nonischemic dilated cardiomyopathy (NIDC) who had received an implantable cardioverter-defibrillator (ICD) for primary prevention.

Background: Extracellular matrix alterations in NIDC might provide electrical heterogeneity, thus potentially contributing to the occurrence of ventricular arrhythmia and subsequent sudden cardiac death (SCD).

Methods: Serum C-terminal propeptide of collagen type-I, C-terminal telopeptide of collagen type-I, matrix metalloproteinase (MMP)-1, and tissue inhibitor of MMP-1 were measured as markers of collagen synthesis and degradation in 70 patients with mild to moderate symptomatic heart failure due to NIDC with left ventricular ejection fraction <35%, who received an ICD for primary prevention of SCD.

Effect of sinus rhythm restoration after electrical cardioversion on apelin and brain natriuretic Peptide prohormone levels in patients with persistent atrial fibrillation.

Because humoral alterations have been implicated in the generation and perpetuation of atrial fibrillation (AF), we aimed to elucidate possible abnormalities in atrial endocrine function in the setting of lone AF. Levels of plasma apelin and amino terminal fragment of the brain natriuretic peptide prohormone (NT-pro-BNP) were measured in 40 patients with persistent AF, before and 1 month after electrical cardioversion, and in 15 controls in sinus rhythm (SR). All patients were successfully cardioverted to SR, although in 9 of them AF recurred.

Sleep patterns in patients with acute coronary syndromes.

Background: Little is known about sleep quality in patients with acute coronary syndromes (ACS) admitted to the coronary care unit (CCU). The aim of this study was to assess nocturnal sleep in these patients, away from the CCU environment, and to evaluate potential connections with the disease process.

Methods: Twenty-two patients with first ever ACS, who were not on sedation or inotropes, underwent a full-night polysomnography (PSG) in our sleep disorders unit within 3 days of the ACS and follow-up PSGs 1 and 6 months later.

New-onset atrial fibrillation as first clinical manifestation of latent Brugada syndrome: prevalence and clinical significance.

Aims: To evaluate the prevalence, clinical significance, and prognosis of latent Brugada syndrome (BrS) in patients with new-onset atrial fibrillation (AF) unmasked by class 1C antiarrhythmic drugs.

Methods And Results: Between January 2000 and June 2008, all consecutive patients with new-onset AF, who after flecainide exhibited typical Brugada ECG pattern, underwent electrophysiologic, pharmacologic, and genetic testing. Among 346 patients [median age 53 years; interquartile range (IQR), 15], 11 (3.

Extracellular matrix alterations in patients with paroxysmal and persistent atrial fibrillation: biochemical assessment of collagen type-I turnover.

Objectives: We investigated whether the serum markers of collagen turnover differed in various forms of atrial fibrillation (AF) and in sinus rhythm (SR) in humans.

Background: Structural alterations and fibrosis have been implicated in the generation and perpetuation of AF.

Methods: Serum C-terminal propeptide of collagen type-I (CICP), C-terminal telopeptide of collagen type-I (CITP), matrix metalloproteinase-1, and tissue inhibitor of matrix metalloproteinases-1 were measured as markers of collagen synthesis and degradation in 70 patients with AF and 20 healthy control subjects in SR.

Electrophysiological effects of carvedilol administration in patients with dilated cardiomyopathy.

Purpose: Several studies suggest the clinical efficacy of carvedilol in reducing atrial and ventricular arrhythmias in patients with left ventricular dysfunction (LVD) due to congestive heart failure (CHF) or following myocardial infarction. However, the mechanisms supporting its antiarrhythmic efficacy have been derived from experimental studies. In this prospective, placebo-controlled trial we examined the electrophysiological effects of a high oral dose of carvedilol in patients with CHF and LVD due to non-ischemic dilated cardiomyopathy.

Evidence of mechanoelectric feedback in the atria of patients with atrioventricular nodal reentrant tachycardia.

Objective: Patients with atrioventricular nodal reentrant tachycardia (AVNRT) could serve as a clinical model to study the effects of mechanical stretch in the electrical properties of atrial myocardium.

Materials And Methods: We studied 14 patients with AVNRT. Peak, mean and minimal atrial pressures, atrial refractoriness (ERP) in the right atrial appendage and high right atrial lateral wall and monophasic action potential duration at 90% of repolarisation (MAPd90) in the right atrial appendage were assessed during atrial pacing at 500 and 400 ms and after 2 min of pacing at the tachycardia cycle length.

Drug therapy for atrial fibrillation.

Although the maintenance of sinus rhythm would be the ideal scenario for patients with atrial fibrillation (AF), recent randomised trials have questioned the value of this approach. A careful interpretation of their results showed the limited efficacy of currently available antiarrhythmic drugs in maintaining sinus rhythm, as well as their potentially serious side effects. Therefore, it is imperative to develop safer and more effective drugs for AF.

Amino-terminal pro-brain natriuretic peptide predicts ventricular arrhythmogenesis in patients with ischemic cardiomyopathy and implantable cardioverter-defibrillators.

Study Objectives: Even in high-risk population groups, not all patients have the same risk of sudden cardiac death (SCD). Given the emerging data about the amino-terminal fragment of the brain natriuretic peptide prohormone (NT-proBNP) value in heart failure, we planned to evaluate the importance of NT-proBNP levels in predicting the occurrence of malignant arrhythmias in patients with ischemic cardiomyopathy and implantable cardioverter-defibrillators (ICDs).

Design: Prospective study.