Pamela K. Mason

Impact of Mechanical Activation, Scar, and Electrical Timing on Cardiac Resynchronization Therapy Response and Clinical Outcomes

OBJECTIVESnUsing cardiac magnetic resonance (CMR), we sought to evaluate the relative influences of mechanical, electrical, and scar properties at the left ventricular lead position (LVLP) on cardiac resynchronization therapy (CRT) response and clinical events.nnnBACKGROUNDnCMR cine displacement encoding with stimulated echoes (DENSE) provides high-quality strain for overall dyssynchrony (circumferential uniformity ratio estimate [CURE] 0 to 1) and timing of onset of circumferential contraction at the LVLP. CMR DENSE, late gadolinium enhancement, and electrical timing together could improve upon other imaging modalities for evaluating the optimal LVLP.nnnMETHODSnPatients had complete CMR studies and echocardiography before CRT. CRT response was defined as a 15% reduction in left ventricular end-systolic volume. Electrical activation was assessed as the time from QRS onset to LVLP electrogram (QLV). Patients were then followed for clinical events.nnnRESULTSnIn 75 patients, multivariable logistic modeling accurately identified the 40 patients (53%) with CRT response (area under the curve: 0.95 [p < 0.0001]) based on CURE (odds ratio [OR]: 2.59/0.1 decrease), delayed circumferential contraction onset at LVLP (OR: 6.55), absent LVLP scar (OR: 14.9), and QLV (OR: 1.31/10 ms increase). The 33% of patients with CURE <0.70, absence of LVLP scar, and delayed LVLP contraction onset had a 100% response rate, whereas those with CURE ≥0.70 had a 0% CRT response rate and a 12-fold increased risk of death; the remaining patients had a mixed response profile.nnnCONCLUSIONSnMechanical, electrical, and scar properties at the LVLP together with CMR mechanical dyssynchrony are strongly associated with echocardiographic CRT response and clinical events after CRT. Modeling these findings holds promise for improving CRT outcomes.

Impact of the CHA2DS2-VASc score on anticoagulation recommendations for atrial fibrillation.

BACKGROUNDnThe Congestive heart failure, Hypertension, Age ≥ 75 years, Diabetes mellitus, Stroke (CHADS(2)) score is used to predict the need for oral anticoagulation for stroke prophylaxis in patients with atrial fibrillation. The Congestive heart failure, Hypertension, Age ≥ 75 years, Diabetes mellitus, Stroke, Vascular disease, Age 65-74 years, Sex category (CHA(2)DS(2)-VASc) schema has been proposed as an improvement. Our objective is to determine how adoption of the CHA(2)DS(2)-VASc score alters anticoagulation recommendations.nnnMETHODSnBetween 2004 and 2008, 1664 patients were seen at the University of Virginia Atrial Fibrillation Center. We calculated the CHADS(2) and CHA(2)DS(2)-VASc scores for each patient. The 2006 American College of Cardiology/American Heart Association/Heart Rhythm Society guidelines for atrial fibrillation management were used to determine anticoagulation recommendations based on the CHADS(2) score, and the 2010 European Society of Cardiology guidelines were used to determine anticoagulation recommendations based on the CHA(2)DS(2)-VASc score.nnnRESULTSnThe average age was 62±13 years, and 34% were women. Average CHADS(2) and CHA(2)DS(2)-VASc scores were 1.1±1.1 and 1.8±1.5, respectively (P<.0001). The CHADS(2) score classified 33% as requiring oral anticoagulation. The CHA(2)DS(2)-VASc score classified 53% as requiring oral anticoagulation. For women, 31% had a CHADS(2) score ≥ 2, but 81% had a CHA(2)DS(2)-VASc score ≥ 2 (P = .0001). Also, 32% of women with a CHADS(2) score of zero had a CHA(2)DS(2)-VASc score ≥ 2. For men, 25% had a CHADS(2) score ≥ 2, but 39% had a CHA(2)DS(2)-VASc score ≥ 2 (P<.0001).nnnCONCLUSIONnCompared with the CHADS(2) score, the CHA(2)DS(2)-VASc score more clearly defines anticoagulation recommendations. Many patients, particularly older women, are redistributed from the low- to high-risk categories.

Independent multicenter study of Riata and Riata ST implantable cardioverter-defibrillator leads.

BACKGROUNDnRiata and Riata ST leads (St Jude Medical, Sylmar, CA) are prone to failure. There are no independent multicenter reports regarding Riata or Riata ST lead performance.nnnOBJECTIVEnTo conduct a retrospective multicenter study of Riata and Riata ST leads that were implanted and followed at 7 centers.nnnMETHODSnThe study included adults who received St Jude Medical Riata or Riata ST leads. Data for Quattro Secure leads were obtained from an earlier study.nnnRESULTSnFrom 2002 to 2010, 1081 patients received a Riata (n = 774) or Riata ST (n = 307) lead. Follow-up was longer for Riata than Riata ST leads (4.2 ± 2.4 years vs 3.3 ± 1.7 years; P<.0001). During the study, 67 leads failed (6.2%), including 62 of 774 Riata (8.0%) and 5 of 307 Riata ST (1.6%) leads. Forty-seven of 67 lead failures (70.1%) were caused by electrical malfunction, and 20 lead failures (29.9%) were due to externalized conductors (ECs) that were electrically intact. Of 110 leads examined fluoroscopically, ECs were found in 26 of 81 Riata (32%) and 1 of 29 Riata ST (3.4%) leads. Of 26 Riata leads with ECs, 7 (27%) were malfunctioning. Riata leads had lower overall and malfunction free survival compared to Quattro leads (P<.0001), while Riata ST lead survival was not different (P = .422).nnnCONCLUSIONSnThe survival of Riata (but not Riata ST) leads was lower than Quattro leads; however, Riata ST leads had significantly shorter follow-up than Riata leads. ECs were common in Riata leads, and more than a quarter of Riata leads that had ECs were malfunctioning. Our observations suggest that systematic fluoroscopic examination of patients with Riata leads is appropriate.

Sonication of Explanted Cardiac Rhythm Management Devices for the Diagnosis of Pocket Infections and Asymptomatic Bacterial Colonization

Background: Correct diagnosis of the causative organism is critical for the treatment of pacemaker and defibrillator pocket infections. No gold standard for this exists, although swab and tissue cultures are frequently used. The purpose of this study was to determine the value of ultrasonication of explanted generators in the diagnosis of pocket infections and asymptomatic bacterial colonization.

New Pharmacological Agents for Arrhythmias

Despite advances in catheter ablation techniques and device-based therapies for cardiac arrhythmias, antiarrhythmic drugs remain essential components of any comprehensive therapeutic strategy. Antiarrhythmic drug therapy, however, has been limited by both incomplete efficacy and a substantial potential for cardiac and extracardiac toxicity. As a result, only a few new antiarrhythmic agents have successfully completed clinical development programs and reached routine clinical usage over the past 20 years.nnAntiarrhythmic drugs may be indicated for ventricular tachycardia, sudden death prevention, or specific types of supraventricular arrhythmia. Implantable cardioverter-defibrillator (ICD) therapy has evolved as the primary treatment for most life-threatening ventricular arrhythmias, and antiarrhythmic drugs for these rhythms are currently mostly used either as acute interventions or as adjuncts to chronic ICD therapy. Although numerous trials have evaluated the effect of antiarrhythmic drugs to decrease ICD shocks or therapies, such data have yet to provide the sole basis for approval for any new agent. At the same time, drug therapy for atrial arrhythmias is often limited by the drug’s simultaneous effects on the ventricles, which has led to efforts to identify ionic channel targets specific to or preferentially located in the atria. The sustained outward K+ current (IKur, encoded by the Kv 1.5 subunit), the acetylcholine-activated outward K+ current (IKAch), and both peak and late atrial Na+ currents have therefore become potential targets for antiarrhythmic drug developers.1–4 Another approach has been to seek agents that synergistically affect multiple channels simultaneously, resulting in a net beneficial effect while minimizing toxicity. Other nontraditional targets for drug therapy that do not directly involve ion channels have also emerged as our understanding of the mechanisms of arrhythmias has improved. As a result, several new compounds are now at or near completion of phase 3 clinical trials, and other promising …

Effectiveness of integrating delayed computed tomography angiography imaging for left atrial appendage thrombus exclusion into the care of patients undergoing ablation of atrial fibrillation

BACKGROUNDnComputed tomography angiography (CTA) can identify and rule out left atrial appendage (LAA) thrombus when delayed imaging is also performed.nnnOBJECTIVEnIn patients referred for CTA to evaluate pulmonary vein anatomy before the ablation of atrial fibrillation (AF) or left atrial flutter (LAFL), we sought to determine the effectiveness of a novel clinical protocol for integrating results of CTA delayed LAA imaging into preprocedure care.nnnMETHODSnAfter making delayed imaging of the LAA part of our routine preablation CTA protocol, we integrated early reporting of preablation CTA LAA imaging results into clinical practice as part of a formal protocol in June 2013. We then analyzed the effectiveness of this protocol by evaluating 320 AF/LAFL ablation patients with CTA imaging during the time period 2012-2014.nnnRESULTSnIn CTA patients with delayed LAA imaging, the sensitivity and negative predictive values for LAA thrombus using intracardiac echocardiography or transesophageal echocardiography (TEE) as the reference standard were both 100%. Intracardiac echocardiography during ablation confirmed the absence of thrombus in patients with negative CTA or negative TEE results. No patients with either negative CTA results or equivocal CTA results combined with negative TEE results had strokes or transient ischemic attacks. Overall, the need for TEE procedures decreased from 57.5% to 24.0% during the 3-year period because of the CTA protocol.nnnCONCLUSIONnClinical integration of CTA delayed LAA imaging into the care of patients having catheter ablation of AF or LAFL is feasible, safe, and effective. Such a protocol could be used broadly to improve patient care.

Effectiveness of Implantation of a Subcutaneous Implantable Cardioverter-Defibrillator in a Patient With Complete Heart Block and a Pacemaker

The subcutaneous implantable cardioverter-defibrillator (S-ICD) represents an important alternative to traditional ICD therapy. The major limitation of this technology is the inability to provide pacing. Here, we present a case of a patient with complete heart block and a pacemaker who underwent placement of an S-ICD. Special considerations had to be taken with regards to evaluation and implantation of the S-ICD because of the pacemaker. In conclusion, implantation of an S-ICD can be done in patients with pacemaker effectively with appropriate electrocardiographic screening, device testing, and programming.

Increasing lead burden correlates with externalized cables during systematic fluoroscopic screening of Riata leads

PurposeRiata and Riata ST defibrillator leads (St. Jude Medical, Sylmar, CA, USA) have been recalled due to increased risk of insulation failure leading to externalized cables. As this mechanical failure does not necessarily correlate with electrical failure, it can be difficult to diagnose. Fluoroscopic screening can identify insulation failure. Studies have suggested that insulation failure is predominantly seen in 8-Fr, single-coil models. Our patients have exclusively dual-coil leads and a high proportion of 7-Fr leads.MethodsFluoroscopic screening was performed in 48 patients with recalled Riata leads. Twenty-three patients had 8-Fr Riata leads and 25 patients had 7-Fr Riata ST leads. Images were recorded in at least three projections and studies were reviewed by seven attending electrophysiologists.ResultsExternalized cables were seen in ten patients (21xa0%), and another five patients (10xa0%) had abnormal cable spacing. All device interrogations showed normal parameters. Patients with abnormal leads had more leads in situ (2.5u2009±u20090.7 vs. 1.6u2009±u20090.8 leads; Pu2009=u20090.002) and a higher rate of nonischemic cardiomyopathy (80 vs. 24xa0%; Pu2009=u20090.03). There were no differences between the groups with regards to patient age, body mass index, lead age, lead parameters, or vascular access site. There was no difference with regard to lead size (Pu2009=u20090.76).ConclusionsThe Riata family of leads has a high incidence of mechanical failure, as demonstrated on fluoroscopic screening. In this study, the 7-Fr models were just as likely to mechanically fail as the 8-Fr models. Increasing lead burden and a diagnosis of nonischemic cardiomyopathy correlated with insulation failure.

Arrhythmia care in a value-based environment: Past, present, and future: Developed and endorsed by the Heart Rhythm Society (HRS)

Fred M. Kusumoto, MD, FHRS (Chair), Steven C. Hao, MD, FHRS (Coach), David J. Slotwiner, MD, FHRS (Coach), Jim W. Cheung, MD, FHRS, Jonathan C. Hsu, MD, FHRS, Marcin Kowalski, MD, FHRS, Ruth A. Madden, MPH, RN, Pamela K. Mason, MD, FHRS, G. Stuart Mendenhall, MD, FHRS, Devi G. Nair, MD, FHRS, Javed M. Nasir, MD, FHRS, Josh R. Silverstein, MD, Brad Sutton, MD, MBA, Khaldoun G. Tarakji, MD, MPH, FHRS, Gaurav A. Upadhyay, MD, FHRS, Emily P. Zeitler, MD, MHS From the Department of Cardiovascular Disease, Mayo Clinic, Jacksonville, Florida, Sutter Pacific Medical Foundation, San Francisco, California, NewYork-Presbyterian/Queens, New York, New York, Weill Cornell Medical College, Cardiology Division, New York, New York, Weill Cornell Medicine, Cardiology, New York, New York, Cardiac Electrophysiology Section, University of California, San Diego, La Jolla, California, Staten Island University, Hospital Northwell Health System New York, New York, Cleveland Clinic, Cleveland, Ohio, University of Virginia Health System, Charlottesville, Virginia, University of Pittsburgh, Pittsburgh, Pennsylvania, St. Bernards Heart & Vascular Center, Jonesboro, Arkansas, Cardiac Electrophysiology and Arrhythmia Service, Stanford University, Stanford, California, Mount Carmel Columbus Cardiology Consultants, New Albany, Ohio, University of Louisville, Louisville, Kentucky, Cleveland Clinic, Cleveland, Ohio, University of Chicago Medical Center, Chicago, Illinois, and Duke University Hospital, Durham, North Carolina.

Unresolved Issues in Implantable Cardioverter-Defibrillator Therapy

Over the last 15 years, a series of well-designed randomized clinical trials has clearly demonstrated that implantable cardioverter-defibrillator (ICD) therapy reduces mortality in select high-risk populations. Despite the widespread acceptance of ICD therapy, many questions related to its optimal use remain. This article discusses several key issues now confronting clinicians.