Brett D. Atwater

Extent of and Reasons for Nonuse of Implantable Cardioverter Defibrillator Devices in Clinical Practice Among Eligible Patients With Left Ventricular Systolic Dysfunction

Background— Several studies that used claims and registry data have reported that 40% to 80% of patients eligible for an implantable cardioverter defibrillator (ICD) fail to receive one in clinical practice, and the rates are especially high among women and blacks. The extent and documented reasons for nonuse of ICDs among patients with left ventricular systolic dysfunction are unknown. Methods and Results— Using hospital claims and clinical data, we identified patients hospitalized with a heart failure diagnosis and left ventricular ejection fraction ⩽30% between January 1, 2007, and August 30, 2007, at a tertiary-care center. Using claims data, we determined placement of an ICD or cardiac resynchronization therapy with defibrillation device at any time up to 1 year after hospitalization. Medical records for patients without an ICD were abstracted to determine reasons for nonuse. Patients with an ICD were compared with patients without an ICD and also with patients without an ICD who did not have any contraindication for an ICD as identified through chart abstraction. Of the 542 potentially eligible patients identified, 224 (41%) did not have an ICD. In the initial adjusted analysis, female sex (odds ratio=1.90; 95% CI, 1.28 to 2.81) and increasing age (odds ratio=1.07; 95% CI, 1.04 to 1.11) were associated with a higher likelihood of not having an ICD. After detailed chart review, of the 224 patients without an ICD, 117 (52%) were ineligible for the device and 38 (17%) patients refused the device, resulting in only 69 (13%) patients eligible for an ICD who failed to receive one. In this subsequent adjusted analysis, remaining factors associated with a higher likelihood of not having an ICD were absence of ventricular arrhythmias (odds ratio=4.93; 95% CI, 2.56 to 9.50), noncardiology hospital service (odds ratio=3.73; 95% CI, 1.98 to 7.04), and lack of health insurance (odds ratio=3.10; 95% CI, 1.48 to 6.46). Conclusions— On the basis of a detailed chart review, the true rate of ICD underuse may be substantially lower than previous estimates. In addition, after accounting for ICD eligibility criteria, patient sex and age disparities in ICD therapy were no longer present.

Prevalence and clinical characteristics associated with left atrial appendage thrombus in fully anticoagulated patients undergoing catheter-directed atrial fibrillation ablation.

LAA Thrombus Among Anticoagulated AF Patients. Introduction: Catheter‐directed atrial fibrillation (AF) ablation is contraindicated among patients with left atrial appendage (LAA) thrombus. The prevalence of LAA thrombus among fully anticoagulated patients undergoing AF ablation is unknown.

Usefulness of the Duke Sudden Cardiac Death Risk Score for Predicting Sudden Cardiac Death in Patients With Angiographic (>75% Narrowing) Coronary Artery Disease

The currently available sudden cardiac death (SCD) risk prediction tools fail to identify most at-risk patients and cannot delineate a specific patients SCD risk. We sought to develop a tool to improve the risk stratification of patients with coronary artery disease. Clinical, demographic, and angiographic characteristics were evaluated among 37,258 patients who had undergone coronary angiography from January 1, 1985 to May 31, 2005, and who were found to have at least one native coronary artery stenosis of > or =75%. After a median follow-up of 6.2 years, SCD had occurred in 1,568 patients, 14,078 patients had died from other causes, and 21,612 patients remained alive. A Cox proportional hazards model identified 10 independent patient characteristic variables significantly associated with SCD. A simplified model accounting for 97% of the predictive capacity of the full model included the following 7 variables: depressed left ventricular ejection fraction, number of diseased coronary arteries, diabetes mellitus, hypertension, heart failure, cerebrovascular disease, and tobacco use. The Duke SCD risk score was created from the simplified model to predict the likelihood of SCD among patients with coronary artery disease. It was internally validated with bootstrapping (c-index = 0.75, chi-square = 1,220.8) and externally validated in patients with ischemic cardiomyopathy from the Sudden Cardiac Death Heart Failure Trial (SCD-HeFT) database (c-index = 0.64, chi-square = 14.1). In conclusion, the Duke SCD risk score represents a simple, validated method for predicting the risk of SCD among patients with coronary artery disease and might be useful for directing treatment strategies designed to mitigate the risk of SCD.

Implantable cardioverter defibrillators: risks accompany the life-saving benefits

Sudden cardiac arrest is the one of the most common causes of death in developed countries and accounts for between 180 000 and over 450 000 per year in the USA. Antiarrhythmic drug approaches to prevention of sudden cardiac death have been resoundingly ineffective. The implantable cardioverter defibrillator (ICD) constitutes one of the most important and well validated therapeutic advances in modern cardiovascular medicine. Consequently, ICD use has increased exponentially, although implementation has been quite variable geographically and with respect to other measures. In view of the expanded use of ICDs, the potential shortcomings and risks of ICD therapy have attracted attention. This commentary summarises the weaknesses, disadvantages and risks of the ICD in a balanced fashion in light of their proven life-saving benefits.

Is heart failure guideline adherence being underestimated? The impact of therapeutic contraindications.

BACKGROUND Several studies based on claims data have reported underutilization of evidence-based heart failure (HF) therapies. The degree to which these estimates fail to account for therapeutic contraindications is unclear. METHODS We identified patients with HF and left ventricular ejection fraction ≤45% seen between January 1, 2010, and July 1, 2010, at a tertiary care Veterans Affairs Medical Center. Medical records were abstracted to evaluate utilization of and contraindications to β-blocker, angiotensin-converting enzyme inhibitor, aldosterone antagonist, anticoagulation for atrial fibrillation, implantable cardioverter-defibrillator, and cardiac resynchronization therapies. RESULTS Of the 178 patients with HF and an ejection fraction ≤45%, 78 (44%) received every guideline-recommended therapy. After accounting for medical contraindications, 77 (72%) of 107 patients received every guideline-recommended therapy. Adherence to recommendations for β-blocker (98%), angiotensin-converting enzyme inhibitor/angiotensin blocker (95%), and anticoagulation (97%) were better than adherence to implantable cardioverter-defibrillator (82%), cardiac resynchronization therapy (59%), or aldosterone antagonist (51%) recommendations. In adjusted analysis, lower New York Heart Association functional class and care by a cardiologist were associated with improved guideline adherence (P < .001). CONCLUSIONS Many patients with HF have therapeutic contraindications, and a failure to account for these may lead to a large underestimation of the true guideline adherence rates.

Platelet glycoprotein IIb/IIIa receptor antagonists in non-ST segment elevation acute coronary syndromes: a review and guide to patient selection.

Platelet glycoprotein (Gp) IIb/IIIa receptor antagonists improve outcomes in patients with acute coronary syndromes without persistent ST-segment elevation, but relative effects depend on appropriate patient selection. Recent data from the CRUSADE (Can Rapid Risk Stratification of Unstable Angina Patients Suppress ADverse Outcomes with Early Implementation of the ACC/AHA Guidelines) quality improvement initiative suggests that GpIIb/IIIa antagonists are underused in clinical practice. The relationship between GpIIb/IIIa inhibition and the magnitude of clinical benefit in the setting of acute coronary syndromes is complex. Several key factors should be considered for proper patient selection, including accurate patient risk stratification, incorporation of these agents with an early invasive management strategy and the concomitant use of other anti-thrombotic therapies. Current practice guidelines for the treatment of patients with non-ST-segment elevation acute coronary syndromes support the integration of an early invasive management with optimal pharmacological therapy, including GpIIb/IIIa antagonists.

The immediate impact of the Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation (COURAGE) trial on the management of stable angina.

The Clinical Outcomes Utilizing Revascularization and Aggressive Drug Evaluation (COURAGE) trial confirmed that percutaneous coronary intervention is no better than optimal medical therapy for the prevention of major adverse cardiac events in patients with stable angina. The impact of these findings on clinical practice remains unknown.

Specificity for each of the 46 criteria of the Selvester QRS score for electrocardiographic myocardial scar sizing in left bundle branch block.

BACKGROUND The Selvester QRS score consists of a set of electrocardiographic criteria designed to identify, quantify and localize scar in the left ventricle using the morphology of the QRS complex. These criteria were updated in 2009 to expand their use to patients with underlying conduction abnormalities, but these versions have thus far only been validated in small and carefully selected populations. AIM To determine the specificity for each of the criteria of the left bundle branch block (LBBB) modified Selvester QRS Score (LB-SS) in a population with strict LBBB and no myocardial scar as verified by cardiovascular magnetic resonance imaging with late gadolinium enhancement (CMR-LGE). METHODS We identified ninety-nine patients with LBBB without scar on CMR-LGE, who underwent a clinically indicated CMR scan at three different centers. The ECG recording date was any time prior to or <30days after the CMR scan. The LB-SS was applied and specificity for detection of scar in each of the 46 separate criteria was determined. RESULTS The specificity ranged between 41% and 100% for the 46 criteria of LB-SS and 27/46 (59%) met ≥95% specificity. The mean±SD specificity was 90%±14%. CONCLUSION Several of the criteria in the LB-SS lack adequate specificity. Elimination or modification of these nonspecific QRS morphology criteria may improve the specificity of the overall LB-SS.

A worldwide experience of the management of battery failures and chronic device retrieval of the Nanostim leadless pacemaker

BACKGROUND The Nanostim leadless pacemaker (LP) met the primary endpoints in an investigational device exemption trial, and was shown to be fully retrievable percutaneously. In October 2016, St Jude Medical issued a worldwide alert of a battery malfunction that caused lost pacing output and LP communication. OBJECTIVE To report the battery failure mechanism and incidence and the worldwide patient management, including device retrieval experiences. METHODS The affected LP battery is a custom lithium-carbon monofluoride cell. These were returned after failure and underwent analysis assessing electronics and battery performance. Data were collected in ongoing clinical studies when LPs were abandoned or retrieved. RESULTS Of 1423 LPs implanted worldwide, there were 34 battery failures, occurring at 2.9 ± 0.4 years with no instances of associated patient injury. Analysis of returned batteries revealed an increase in battery resistance caused by insufficient electrolyte availability at the cathode/anode interface. A total of 66 of 73 retrieval attempts were successful (90.4%; implant duration range: 0.2-4.0 years). The LP docking button was inaccessible in 6 patients, and the docking button detached from the LP during retrieval in 1 patient. There was 1 case of arteriovenous fistula and another case of the LP docking button migrating into the pulmonary artery. There were also 115 non-LP retrieval patients after the advisory who received an additional pacemaker, with no adverse device-to-device interactions reported. CONCLUSION As with standard pacers, LPs can have critical battery failures. Chronic retrieval of LPs is safe and efficacious.

ECG myocardial scar quantification predicts reverse left ventricular remodeling and survival after cardiac resynchronization therapy implantation: A retrospective pilot study.

INTRODUCTION Electrocardiographic (ECG) LV scar quantification may improve prediction of CRT response. METHODS AND RESULTS Data were abstracted in 76 patients who underwent a first CRT implantation at 2 US centers. Selvester QRS scar quantification was performed using the LBBB modified QRS scoring method. Seven clinical variables previously associated with reverse LV remodeling (RLVR) and QRS score were included in logistic regression analysis. Survival was compared across QRS score quartiles using Kaplan-Meier curves. RLVR occurred more frequently in patients with QRS score ≤ 5 (63%) than QRS score>5 (22%), (OR=5.83, 95% CI=2.11-16.07). After adjustment for clinical variables using logistic regression, QRS score>5 predicted RLVR (Chi-square=20.3, P=0.005, AUC=0.782). Patients in the lowest quartile of QRS score (<4) had improved survival compared to patients in the other QRS score quartiles (P=0.037). CONCLUSION ECG quantified LV scar predicts RLVR and long-term survival in patients with LBBB undergoing CRT implantation.