Publications

Acquired and hereditary long-QT syndromes are important causes of sudden cardiac death. Both categories are characterized by abnormally prolonged cardiac repolarization arising from a complex interaction between genetic and environmental factors. This produces a potentially dangerous substrate for polymorphic ventricular tachycardia and sudden cardiac death. In this review, the pathophysiologic, diagnostic, and prognostic features of long-QT syndromes, as well as recommendations regarding therapy, are reviewed.

Cardiac resynchronization therapy (CRT) improves symptoms and prolongs life in selected patients with heart failure and systolic dysfunction. Newer studies suggest important benefits in earlier stages of heart failure, which may stave off future development of severe symptoms and may even improve cardiomyopathy primarily. CRT can be offered with and without defibrillator therapy, which may extend its potential to prolong life at the cost of increased complications. However, no formal guidelines exist regarding the content of informed consent for CRT. Considerations regarding quality of life, length of life and personal autonomy may influence device selection, and clinical uncertainty regarding the likelihood of individual response to therapy adds further challenges to decision-making. As indications for implantation expand, these features of CRT should be explicitly included in the informed consent process to help physicians and patients make individualized choices and guide them through complex decisions.

Cardiac implantable electrical devices (CIEDs) are increasingly common interventions for a wide spectrum of cardiovascular diseases. Caring for patients with life-sustaining devices such as CIEDs at the end of life raises legal and ethical challenges. In 2010, the Heart Rhythm Society (HRS) published an expert consensus statement to review the principles and practice of CIED deactivation. This statement addressed a wide range of ethical and legal principles while providing guidance for communication, decision-making, and procedures in a variety of settings. In this article, we provide a summary of the HRS guidelines and highlight the most important features of CIED deactivation for the practicing clinician.

AIMS: Cardiac resynchronization therapy (CRT) improves echocardiographic parameters, symptoms, hospitalizations, and mortality in patients with New York Heart Association (NYHA) Class III or IV symptoms with left ventricular systolic dysfunction, sinus rhythm, and a prolonged QRS duration. The effectiveness of CRT in patients with mild heart failure symptoms has not been systematically reviewed.

METHODS AND RESULTS: Randomized controlled trials of CRT in patients with NYHA Class I or II heart failure were identified from MEDLINE and EMBASE. The effects of CRT on left ventricular remodelling at 1 year were systematically reviewed, and the effects of CRT on clinical outcomes at 1 year were meta-analysed. Two studies met the pre-specified search criteria, with a total of 2430 patients (REVERSE n = 610 and MADIT-CRT n = 1820). CRT was associated with a reduction in heart failure events in both trials [combined OR 0.57, 95% confidence interval (CI) 0.46-0.70], but not mortality (combined OR 0.96, 95% CI 0.67-1.36). The effect of CRT on the combined endpoint of heart failure events or death favoured CRT (OR 0.63, 95% CI 0.51-0.77). CRT was also associated with improvement in left ventricular remodelling parameters in both studies, including a greater increase in left ventricular ejection fraction in the CRT group than in the control group, at 1 year after randomization. Serious adverse events were rare with CRT.

CONCLUSION: CRT reduces heart failure events in patients with mild heart failure symptoms, left ventricular dysfunction, sinus rhythm, and prolonged QRS duration.

Low-flow, low-gradient aortic stenosis is a heterogeneous entity that encompasses truly severe aortic stenosis as well as mild-to-moderate aortic stenosis in which aortic valve orifice area is severely reduced primarily due to left ventricular (LV) contractile dysfunction. Under such circumstances the capacity of the LV to generate stroke-work is severely compromised. In this case report, we describe a patient with severe LV dysfunction and ventricular dyssynchrony due to right ventricular pacing who presented with decompensated heart failure in the setting of low-flow, low-gradient aortic stenosis. We discuss the management of this high-operative-risk patient, who ultimately underwent upgrading of his dual chamber pacemaker to a biventricular pacemaker with significant echocardiographic, haemodynamic, and clinical improvement.

BACKGROUND: Despite the high prevalence of pacemakers and implantable cardioverter-defibrillators, little is known about physicians' views surrounding the ethical and legal aspects of managing these devices at the end of life.

OBJECTIVE: The purpose of this study was to identify physicians' experiences and views surrounding the ethical and legal aspects of managing cardiac devices at the end of life.

METHODS: Survey questions were administered to internal medicine physicians and subspecialists at a tertiary care center. Physicians were surveyed about their clinical experience, legal knowledge, and ethical beliefs relating to the withdrawal of PM and ICD therapy in comparison to other life-sustaining therapies.

RESULTS: Responses were obtained from 185 physicians. Compared to withdrawal of PMs and ICDs, physicians more often reported having participated in the withdrawal or removal of mechanical ventilation (86.1% vs 33.9%, P <.0001), dialysis (60.6% vs 33.9%, P <.001), and feeding tubes (73.8% vs 33.9%, P <.0001). Physicians were consistently less comfortable discussing cessation of PMs and ICDs compared to other life-sustaining therapies (P <.005). Only 65% of physicians correctly identified the legal status of euthanasia in the United States, and 20% accurately reported the legal status of physician-assisted suicide in the United States. Compared to deactivation of an ICD, physicians more often characterized deactivation of a PM in a pacemaker-dependent patient as physician-assisted suicide (19% vs 10%, P = .027) or euthanasia (9% vs 1%, P <.001).

CONCLUSION: In this single-center study, internists were less comfortable discussing cessation of PM and ICD therapy compared to other life-sustaining therapies and lacked experience with this practice. Education regarding the legal and ethical parameters of device deactivation is needed.

The quality of clinical data submitted by manufacturers to support Food and Drug Administration cardiovascular device premarket approval (PMA) applications varies widely and formal quality assessment has not been previously performed. This study evaluated all original cardiovascular device PMAs with Food and Drug Administration decisions between January 1, 2000, and December 31, 2007, to assess the quality of clinical investigations submitted by manufacturers. Effectiveness and safety end points were judged high quality if they were clearly defined and associated with a specific time point for analysis. Subject accounting was high quality if 90% or greater of the original cohort was accounted for at study conclusion. In total, 88 cardiovascular device PMAs (77.3% permanent implants), 132 clinical studies, 37,328 study subjects (age 61.0 +/- 14.5 years, 33.9% women, 86.3% white), and 29,408 device recipients were analyzed. All PMAs contained clinical data. Primary effectiveness end points, primary safety end points, and subject accounting were deemed high quality in 81.8%, 60.2%, and 77.3% of pivotal studies, respectively. Key cardiovascular comorbidities (coronary artery disease 51.1%, diabetes 36.6%, hypertension 35.2%, heart failure 37.5%, tobacco use 31.8%) and race (14.8%) were infrequently reported, and studies rarely included patients younger than 18 years of age (10.2% of studies). Poorly defined safety and effectiveness end points, poor patient accounting, and incomplete collection of important patient comorbidities make device safety and effectiveness assessments more challenging. Women, pediatric, and nonwhite populations are underrepresented in premarket cardiovascular clinical trials. Manufacturers, regulators, and the clinical community should collaborate to address these study shortcomings to ensure that patients are treated with reliable, safe, and clinically useful medical devices.