Miguel A. Leal

Atrial Fibrillation and Acid Reflux Disease

To date, the precise mechanism of atrial fibrillation (AF) as a possible cause of reflux disease remains uncertain, although some possibilities can be postulated. Inflammation and vagal stimulation may have a key role linking these 2 common diseases. There is some evidence in the form of case reports and limited observational studies reporting that reflux disease, and more specifically esophagitis, can cause paroxysmal AF, and various mechanisms have been proposed. Some studies have demonstrated that acid suppressive therapy by proton pump inhibitors (PPIs) may help ameliorate symptoms associated with AF and also facilitate conversion to normal sinus rhythm in a subset of patients. Further prospective studies are needed to determine if a true causal mechanism exists between the two and assess whether the mechanism is dependent on a specific subtype of AF. In addition, the response of AF‐related symptoms to PPI therapy and the potential for PPI therapy to reduce the development of AF merits further investigation. Clin. Cardiol. 2011 DOI: 10.1002/clc.21969

Atrial fibrosis: a risk stratifier for atrial fibrillation.

Atrial fibrillation (AF), especially persistent and long-standing persistent AF, may result in electroanatomical changes in the left atrium, resulting in remodeling and deposition of fibrous tissue. There are emerging data that atrial substrate modification may increase the risk of thromboembolic complications, including stroke. Several studies have reported that atrial fibrosis is due to complex interactions among several cellular and neurohumoral mediators. Late gadolinium enhancement MRI has been reported to allow quantitative assessment of myocardial fibrosis in patients at risk of developing a stroke. Current stroke risk stratification criteria for AF do not utilize atrial fibrosis as an independent risk factor despite its association with AF and stroke. Further research is required in developing adequate risk stratification tools for predicting the stroke risk and catheter ablation outcomes in AF.

Techniques for Successful Early Retrieval of the Micra Transcatheter Pacing System: A Worldwide Experience

BACKGROUND Experience with retrieval of the Micra transcatheter pacing system (TPS) is limited because of its relatively newer technology. Although abandonment of the TPS at end of life is recommended, certain situations such as endovascular infection or device embolization warrant retrieval. OBJECTIVE The purpose of this study was to report the worldwide experience with successful retrieval of the Micra TPS. METHODS A list of all successful retrievals of the currently available leadless pacemakers (LPs) was obtained from the manufacturer of Micra TPS. Pertinent details of retrieval, such as indication, days postimplantation, equipment used, complications, and postretrieval management, were obtained from the database collected by the manufacturer. Other procedural details were obtained directly from the operators at each participating site. RESULTS Data from the manufacturer consisted of 40 successful retrievals of the Micra TPS. Operators for 29 retrievals (73%) provided the consent and procedural details. Of the 29 retrievals, 11 patients underwent retrieval during the initial procedure (immediate retrieval); the other 18 patients underwent retrieval during a separate procedure (delayed retrieval). Median duration before delayed retrieval was 46 days (range 1-95 days). The most common reason for immediate retrieval was elevated pacing threshold after tether removal. The most common reasons for delayed retrieval included elevated pacing threshold at follow-up, endovascular infection, and need for transvenous device. Mean procedure duration was 63.11 ± 56 minutes. All retrievals involved snaring via a Micra TPS delivery catheter or steerable sheath. No serious complications occurred during the reported retrievals. CONCLUSION Early retrieval of the Micra TPS is feasible and safe.

Injectable loop recorder implantation in an ambulatory setting by advanced practice providers: Analysis of outcomes

Implantable loop recorder (ILR) insertion has historically been performed in a surgical environment such as the electrophysiology (EP) lab. The newest generation loop recorder (Medtronic Reveal LINQ™, Minneapolis, MN, USA) is injectable with potential for implantation in a non‐EP lab setting by advanced practice providers (APPs) facilitating improved workflow and resource utilization. We report the safety and efficacy of injectable ILR placement in the ambulatory care setting by APPs.

Cardiovascular Effects of Methadone

Methadone is a synthetic opioid commercially available as methadone hydrochloride. It is frequently used in the clinical setting as replacement therapy in patients with history of drug abuse and, in the recent past, also as an analgesic. Some of its characteristics, such as a long elimination half-life, good analgesic efficacy, and also low cost have increased the prescription of this medication for patients with chronic pain. Methadone works primarily as an agonist on opiate receptors in the central nervous system and in organs composed of smooth muscle tissue. It shares the potential to cause drug addiction with psychological dependence, physical dependence, and tolerance. Major hazards related to drug overdose include respiratory depression, circulatory depression, respiratory arrest, shock, and cardiac arrest, with the cardiovascular effects being in part secondary to intense sympathomimetic stimulation along with block of important cardiac ion channels, which can result in QT interval prolongation and potentially lethal cardiac arrhythmias. Patients who start or continue chronic therapy with methadone require careful management and monitoring in order to identify and correct undesirable side effects or adverse reactions, as well as unfavorable drug–drug interactions.

Aspirin in stroke prevention in nonvalvular atrial fibrillation and stable vascular disease: an era of new anticoagulants

Atrial fibrillation (AF) is a major cause of ischemic stroke, especially in the elderly. There are currently enough data to support the notion that anticoagulation with warfarin or dabigatran is far superior to aspirin in the prevention of stroke or systemic embolism in AF. Aspirin is the preferred modality in patients who are either not candidates for anticoagulation, such as patients with increased risk for bleeding, low-risk patients based on the CHADS2 score or patients who have difficulty in maintaining a therapeutic international normalized ratio. There is no dispute on the recommendations regarding stroke prevention in high-risk patients (CHADS2 risk score of 2 and beyond) with AF. However, there is some controversy regarding the appropriate strategy (anticoagulation vs aspirin) for stroke prevention in low-risk patients (CHA2DS2-VASc score of 0–1). Novel oral anticoagulant drugs (direct thrombin inhibitors and Factor Xa inhibitors) might further diminish the role of aspirin for stroke prevention in AF due to their superior efficacy, lack of need for monitoring of therapeutic effects and lower bleeding risk when compared with warfarin, especially in patients with stable vascular disease.

Ventricular Arrhythmias in the Elderly: Evaluation and Medical Management

Ventricular arrhythmias constitute the main cause of sudden cardiac death. In the elderly, their presentation may be manifested by intermittent confusion or unexplained falls. In some cases, they may also be asymptomatic. The primary management goals are to identify and treat the underlying cause and prevent recurrence. With the exception of beta-blockers, none of the other antiarrhythmic drugs available reduce mortality associated with ventricular arrhythmias. In the elderly, these drugs are associated with a higher risk of adverse events. In this article, the authors review the data available regarding evaluation and management of ventricular arrhythmias in the elderly.

P‐Wave Amplitude and PR Changes in Patients With Inappropriate Sinus Tachycardia: Findings Supportive of a Central Mechanism

Background The mechanism of inappropriate sinus tachycardia (IST) remains incompletely understood. Methods and Results We prospectively compared 3 patient groups: 11 patients with IST (IST Group), 9 control patients administered isoproterenol (Isuprel Group), and 15 patients with cristae terminalis atrial tachycardia (AT Group). P‐wave amplitude in lead II and PR interval were measured at a lower and higher heart rate (HR1 and HR2, respectively). P‐wave amplitude increased significantly with the increase in HR in the IST Group (0.16±0.07 mV at HR1=97±12 beats per minute versus 0.21±0.08 mV at HR2=135±21 beats per minute, P=0.001). The average increase in P‐wave amplitude in the IST Group was similar to the Isuprel Group (P=0.26). PR interval significantly shortened with the increases in HR in the IST Group (146±15 ms at HR1 versus 128±16 ms at HR2, P<0.001). A similar decrease in the PR interval was noted in the Isuprel Group (P=0.6). In contrast, patients in the atrial tachycardia Group experienced PR lengthening during atrial tachycardia when compared with baseline normal sinus rhythm (153±25 ms at HR1=78±17 beats per minute versus 179±29 ms at HR2=140±28 beats per minute, P<0.01). Conclusions We have shown that HR increases in patients with IST were associated with an increase in P‐wave amplitude in lead II and PR shortening similar to what is seen in healthy controls following isoproterenol infusion. The increase in P‐wave amplitude and absence of PR lengthening in IST support an extrinsic mechanism consistent with a state of sympatho‐excitation with cephalic shift in sinus node activation and enhanced atrioventricular nodal conduction.

Seal plug damage causing inappropriate detection and therapy in a subcutaneous defibrillator system.

Introduction Subcutaneous implantable cardioverter-defibrillator (S-ICD) systems have been introduced to clinical electrophysiology within the past decade as an alternative to the implant of traditional transvenous devices in the management of patients with increased risk for ventricular tachyarrhythmias and sudden cardiac death. These devices have the unique ability to terminate ventricular tachycardia (VT) and/or ventricular fibrillation (VF) with no direct contact between the implanted hardware and the vasculature or the endocardium. The electrical discharge is delivered between a can that is implanted in the left lateral thoracic region and a coil that is placed lateral to the left edge of the sternum, anterior to the rib cage. Although initial reports indicated an acceptable rate of inappropriate sensing and therapies when this technology is compared to traditional transvenous systems, novel mechanisms of noise oversensing that may lead to inappropriate detection and shocks have recently been reported. The present report illustrates a mechanism of noise oversensing triggered by fluid entrapment within the device header secondary to a physical breach of the seal plug.