Amy Leigh Miller

Ventricular arrhythmias and sudden cardiac death

Management strategies for ventricular arrhythmias are guided by the risk of sudden death and severity of symptoms. Patients with a substantial risk of sudden death usually need an implantable cardioverter defibrillator (ICD). Although ICDs effectively end most episodes of ventricular tachycardia or ventricular fibrillation and decrease mortality in specific populations of patients, they have inherent risks and limitations. Generally, antiarrhythmic drugs do not provide sufficient protection from sudden death, but do have a role in reducing arrhythmias that cause symptoms. Catheter ablation is likewise important for reducing the frequency of spontaneous arrhythmias and is curative for some patients, usually those with idiopathic arrhythmias and no heart disease. Arrhythmia surgery is now infrequent, offered by only a few specialised centres for refractory arrhythmias. Advances in understanding of genetic arrhythmia syndromes and in technology for mapping and ablation of ventricular arrhythmias, and enhanced algorithms in implantable devices for rhythm management, have contributed to improved outcomes.

Ventricular Tachycardia in Cardiac Sarcoidosis: Characterization of Ventricular Substrate and Outcomes of Catheter Ablation

Background—Cardiac sarcoid–related ventricular tachycardia (VT) is a rare disorder; the underlying substrate and response to ablation are poorly understood. We sought to examine the ventricular substrate and outcomes of catheter ablation in this population. Methods and Results—Of 435 patients with nonischemic cardiomyopathy referred for VT ablation, 21 patients (5%) had cardiac sarcoidosis. Multiple inducible VTs were observed with mechanism consistent with scar-mediated re-entry in all VTs. Voltage maps showed widespread and confluent right ventricular scarring. Left ventricular scarring was patchy with a predilection for the basal septum, anterior wall, and perivalvular regions. Epicardial right ventricular scar overlay and exceeded the region of corresponding endocardial scar. After ≥1 procedures, ablation abolished ≥1 inducible VT in 90% and eliminated VT storm in 78% of patients; however, multiple residual VTs remained inducible. Failure to abolish all inducible VTs was because of septal intramural circuits or extensive right ventricular scarring. Multiple procedure VT-free survival was 37% at 1 year, but VT control was achievable in the majority of patients with fewer antiarrhythmic drugs compared with preablation (2.1±0.8 versus 1.1±0.8; P<0.001). Conclusions—Patients with cardiac sarcoidosis and VT exhibit ventricular substrate characterized by confluent right ventricular scarring and patchy left ventricular scarring capable of sustaining a large number of re-entrant circuits. Catheter ablation is effective in terminating VT storm and eliminating ≥1 inducible VT in the majority of patients, but recurrences are common. Ablation in conjunction with antiarrhythmic drugs can help palliate VT in this high-risk population.

Implantable Cardioverter-Defibrillator Use Among Medicare Patients With Low Ejection Fraction After Acute Myocardial Infarction.

IMPORTANCE Implantable cardioverter-defibrillators (ICDs) are not recommended within 40 days of myocardial infarction (MI); thus, ICD implantation might not be considered during the post-MI care transition. OBJECTIVE To examine ICD implantation rates and associated mortality among older MI patients with low ejection fraction (EF). DESIGN, SETTING, AND PARTICIPANTS Retrospective observational study of Medicare beneficiaries with an EF of 35% or less after MI, treated at 441 US hospitals between 2007 and 2010, excluding patients with prior ICD implantation. Follow-up data were available through December 2010. EXPOSURES ICD implantation within 1 year of MI vs no ICD implantation within 1 year of MI. MAIN OUTCOMES AND MEASURES Patient characteristics associated with receiving an ICD within 1 year after discharge and 2-year mortality associated with ICD implantation. RESULTS Among 10,318 MI patients with EF of 35%or lower, the cumulative 1-year ICD implantation rate was 8.1% (95%CI, 7.6%-8.7%). Patients with ICD implantation were more likely to have prior coronary artery bypass graft procedures, higher peak troponin levels, in-hospital cardiogenic shock, and cardiology follow-up within 2 weeks after discharge relative to patients who did not receive an ICD within 1 year. Implantation of ICD was associated with lower 2-year mortality (15.3 events per 100 patient-years [128 deaths in 838 patient-years] vs 26.4 events per 100 patient-years [3033 deaths in 11 479 patient-years]; adjusted HR, 0.64; 95%CI, 0.53-0.78). [table: see text] CONCLUSIONS AND RELEVANCE In this large registry study of older patients who experienced MI from 2007-2010, fewer than 1 in 10 eligible patients with low EF received an ICD within 1 year after MI, although ICD implantation was associated with lower risk-adjusted mortality at 2 years. Additional research is needed to determine evidence-based approaches to increase ICD implantation among eligible patients.

Event-free survival following CRT with surgically implanted LV leads versus standard transvenous approach.

Background:  While surgical epicardial lead placement is performed in a subset of cardiac resynchronization therapy patients, data comparing survival following surgical versus transvenous lead placement are limited. We hypothesized that surgical procedures would be associated with increased mortality risk.

Failure to reassess ejection fraction after acute myocardial infarction in potential implantable cardioverter/defibrillator candidates: Insights from the Translational Research Investigating Underlying disparities in acute Myocardial infarction Patients' Health Status (TRIUMPH) registry

BACKGROUND Current practice guidelines advocate delaying assessment of primary prevention implantable cardioverter/defibrillator (ICD) candidacy at least 40 days after an acute myocardial infarction (AMI) because early ICD implantation after AMI has not demonstrated survival benefit. The rate at which interval reassessment of left ventricular ejection fraction (LVEF) occurs in potential primary prevention ICD candidates is unknown. METHODS We examined patients with AMI in the TRIUMPH registry with inhospital LVEF <40% discharged alive after their index presentation, excluding patients with a prior ICD and those who declined ICD during the index admission or were discharged to hospice. We conducted multivariable Poisson modeling to identify independent factors associated with LVEF reassessment by 6 months after AMI. RESULTS Of the 533 patients meeting the inclusion criteria, only 187 (35.1%) reported LVEF reassessment in the first 6 months after AMI and only 13 patients (2.4%) underwent ICD implantation by 1 year. In multivariable analysis, early cardiology follow-up after AMI was associated with a higher likelihood of LVEF reassessment (odds ratio 1.16, 95% confidence interval 1.06-1.28), whereas uninsured status and cardiologist-driving inpatient medical decision making were associated with a lower likelihood of LVEF reassessment (odds ratios 0.84 [95% CI 0.74-0.96] and 0.78 [95% CI 0.68-0.91], respectively). CONCLUSIONS In contemporary practice, almost 2 of 3 potential primary prevention ICD candidates did not report follow-up LVEF evaluation, with a very low rate of ICD implantation at 1 year. These results suggest an important gap in quality, highlighting the need for better transitions of care.

Optimal Medical Therapy Use Among Patients Receiving Implantable Cardioverter/Defibrillators: Insights From the National Cardiovascular Data Registry

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Clinical problem-solving. Out of the blue.

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Left Ventricular Ejection Fraction Assessment Among Patients With Acute Myocardial Infarction and Its Association With Hospital Quality of Care and Evidence-Based Therapy Use

Background—The left ventricular ejection fraction (LVEF) has prognostic and therapeutic utility after acute myocardial infarction (AMI). Although LVEF assessment is a key performance measure among AMI patients, contemporary rates of in-hospital assessment and its association with therapy use have not been well characterized. Methods and Results—We examined rates of in-hospital LVEF assessment among 77 982 non–ST-elevation myocardial infarction patients and 50 863 ST-elevation myocardial infarction patients in Acute Coronary Treatment and Intervention Outcomes Network Registry–Get With The Guidelines between January 2007 and September 2009, after excluding patients who died in-hospital or who were transferred to another acute care facility, discharged to end-of-life care, or had missing LVEF assessment status. LVEF assessment increased significantly over time, with higher rates among ST-elevation myocardial infarction than non–ST-elevation myocardial infarction patients (95.1% versus 91.6%; P<0.001). Excluding patients with prior heart failure did not alter these observations. Significant interhospital variability in LVEF assessment rates was observed. Compared with patients with in-hospital LVEF assessment, patients who did not have LVEF assessed were older and more likely to have clinical comorbidities. In multivariable modeling, lower overall hospital quality of AMI care was also associated with lower likelihood of LVEF assessment (odds ratio for failure to assess LVEF, 1.09; 95% confidence interval, 1.05–1.13 per 10% decrease in defect-free care). Patients with in-hospital LVEF assessment were more likely to be discharged on evidence-based secondary prevention medication therapies compared with paients without LVEF assessment. Conclusions—The assessment of LVEF among patients with AMI has improved significantly over time, yet significant interhospital variability exists. Patients who did not have in-hospital LVEF assessment were less likely to receive evidence-based medications at discharge. These patients represent targets for future quality improvement efforts.

A Heavy Heart

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Pacing as a treatment for reflex-mediated (vasovagal, situational, or carotid sinus hypersensitivity) syncope: A systematic review for the 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope: A report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society

OBJECTIVES To determine, using systematic review of the biomedical literature, whether pacing reduces risk of recurrent syncope and relevant clinical outcomes among adult patients with reflex-mediated syncope. METHODS MEDLINE (through PubMed), EMBASE, and the Cochrane Central Register of Controlled Trials (through October 7, 2015) were searched for randomized trials and observational studies examining pacing and syncope, and the bibliographies of known systematic reviews were also examined. Studies were rejected for poor-quality study methods and for the lack of the population, intervention, comparator, or outcome(s) of interest. RESULTS Of 3,188 citations reviewed, 10 studies met the inclusion criteria for systematic review, including a total of 676 patients. These included 9 randomized trials and 1 observational study. Of the 10 studies, 4 addressed patients with carotid sinus hypersensitivity, and the remaining 6 addressed vasovagal syncope. Among the 6 open-label (unblinded) studies, we found that pacing was associated with a 70% reduction in recurrent syncope (relative risk [RR]: 0.30; 95% confidence interval [CI]: 0.15-0.60). When the 2 analyzable studies with double-blinded methodology were considered separately, there was no clear benefit (RR: 0.73; 95% CI: 0.25-2.1), but confidence intervals were wide. The strongest evidence was from the randomized, double-blinded ISSUE-3 (Third International Study on Syncope of Uncertain Etiology) trial, which demonstrated a benefit of pacing among patients with recurrent syncope and asystole documented by implantable loop recorder. CONCLUSIONS There are limited data with substantive evidence of outcome ascertainment bias, and only 2 studies with a double-blinded study design have been conducted. The evidence does not support the use of pacing for reflex-mediated syncope beyond patients with recurrent vasovagal syncope and asystole documented by implantable loop recorder.