Three Questions for Evidence-Based Cardiac Electrophysiology

Have the Findings from Clinical Risk Prediction and Trials Any Key Messages for Safety Pharmacology?

Anti-arrhythmic drugs are a mainstay in the management of symptoms related to arrhythmias, and are adjuncts in prevention and treatment of life-threatening ventricular arrhythmias. However, they also have the potential for pro-arrhythmia and thus the prediction of arrhythmia predisposition and drug response are critical issues. Clinical trials are the latter stages in the safety testing and efficacy process prior to market release, and as such serve as a critical safeguard. In this review, we look at some of the lessons to be learned from approaches to arrhythmia prediction in patients, clinical trials of drugs used in the treatment of arrhythmias, and the implications for the design of pre-clinical safety pharmacology testing.

A Critical Reappraisal of the Current Clinical Indications to Cardiac Resynchronisation Therapy

Cardiac resynchronisation therapy (CRT) is a well-established non-pharmacological treatment option for patients with refractory symptomatic heart failure (HF) already under optimal medical therapy. CRT is founded on the principle that interventricular conduction disturbances and more in particular left bundle branch block (LBBB) are deleterious to cardiac performance, and may contribute to the systolic and diastolic incompetency typical of patients with HF. Although CRT is associated with a not negligible percentage of non-response, all the international guidelines on chronic HF have extended their indications to CRT, also to patients with less symptomatic HF who are already showing signs of systolic dysfunction and interventricular dyssynchrony, without giving any substantial advice to reduce the number of failures of this therapy. This review seeks to point out the potential issues linked to CRT, with the aim of making a reappraisal of the clinical evidences supporting the current indications to CRT, and to figure out which type of research should be warranted in the field for the future to reduce the percentage of non-responders to this therapy.

Resynchronization: considering device-based cardiac therapy in older adults

Cardiac resynchronization therapy (CRT) is a device-based treatment available to select individuals with systolic heart failure (HF), a large proportion of whom are aged 65 and older. As the field of CRT advances, together with shifting demographics and expanded indications for implantation, there is a need for practitioners caring for older adults to understand what is and is not known about the use of CRT specifically in this population. Clinical trials demonstrating benefits for severe and mild HF have uncertain generalizability to older adults. Other studies demonstrate that device-related complications may be more common with CRT than with simpler devices and more common in older adults. CRT clinical trials also may not adequately capture outcomes and concerns specific to older adults, including quality of life and end-of-life care experiences. Informed decision-making by clinicians, policy-makers, and patients will require greater understanding of the use and outcomes of CRT in older persons.

Indications for cardiac resynchronization therapy: 2011 update from the Heart Failure Society of America Guideline Committee

Cardiac resynchronization therapy (CRT) improves survival, symptoms, quality of life, exercise capacity, and cardiac structure and function in patients with New York Heart Association (NYHA) functional class II or ambulatory class IV heart failure (HF) with wide QRS complex. The totality of evidence supports the use of CRT in patients with less severe HF symptoms. CRT is recommended for patients in sinus rhythm with a widened QRS interval (≥150 ms) not due to right bundle branch block (RBBB) who have severe left ventricular (LV) systolic dysfunction and persistent NYHA functional class II-III symptoms despite optimal medical therapy (strength of evidence A). CRT may be considered for several other patient groups for whom evidence of benefit is clinically significant but less substantial, including patients with a QRS interval of ≥120 to <150 ms and severe LV systolic dysfunction who have persistent mild to severe HF despite optimal medical therapy (strength of evidence B), some patients with atrial fibrillation, and some with ambulatory class IV HF. Several evidence gaps remain that need to be addressed, including the ideal threshold for QRS duration, QRS morphology, lead placement, degree of myocardial scarring, and the modality for evaluating dyssynchrony. Recommendations will evolve over time as additional data emerge from completed and ongoing clinical trials.