Implantable cardioverter defibrillators: Uses, abuses, gains and complications

Sudden cardiac death (SCD) due to a ventricular arrhythmia is one of the most common causes of death, yet its management continues to be a challenge. Controlled clinical trials have provided evidence that implantable cardioverter defibrillators (ICDs) are effective in reducing the risk of SCD in selected patients with ischaemic or non-ischaemic cardiomyopathy and/or ventricular arrhythmias. As increasing numbers of patients become eligible for ICDs, deciding whom should receive these becomes more complex, especially in patients with borderline risk factors and those with co-morbidities in whom the risk of death from nonarrhythmic cardiovascular cause is higher. What type of ICD a patient should receive remains a challenge. While ICD shocks themselves can affect outcomes adversely, no other therapy has proven more effective to date. Risks of implantation include infection, lead dislodgement and perforation. An ongoing challenge which also needs to be addressed includes whom will be footing the bill for device implants. More data is required to determine which patient population will benefit the most from ICD implants

Resting Sinus Heart Rate and First Degree AV block: Modifiable Risk Predictors or Epiphenomena?

Simple and cost-effective tools that identify patients at increased risk for adverse cardiovascular events are actively sought. High resting sinus heart rate and first degree AV block are easily recognized and commonly encountered findings in a cardiology practice. A growing body of epidemiological and clinical evidence has been shown them to be independent predictors of all-cause and cardiovascular mortality, both in the general population and in patients with structural heart disease. This paper reviews the important role of heart rate and first degree AV block in predicting cardiovascular outcomes, examines the pathophysiological mechanisms underlying this increased risk, and discusses the effectiveness of available therapies to favorably modify these risk factors

Advances in the management of atrial fibrillation in congestive heart failure

Atrial fibrillation, a common problem in patients with heart failure, is associated with increased mortality and morbidity. Pharmacological as well as invasive management and the endpoints of such management are complex. Recent randomized trials indicate that a rate-control strategy, along with anticoagulation treatment with warfarin, when appropriate, has a similar outcome in terms of mortality and morbidity as rhythm control, and could, therefore, be considered as the primary management strategy for atrial fibrillation in patients with heart failure

Characterization of double potentials in human atrial flutter: Studies during transient entrainment

AbstractDouble potentials, defined as atrial electrograms with two discrete deflections per beat separated by an isoelectric interval or a low amplitude baseline, have been observed during right atrial endocardial mapping of human atrial flutter. In this study, bipolar atrial electrograms were recorded during atrial flutter (mean cycle length 235 ± 27 ms [± SEM]) from the high Right atrium, the His bundle region, the coronary sinus and at least 30 right atrial endocardial napping sites in 10 patients. Double potentials were recorded from the right atrium in all patients during atrial flutter.Double potentials were evaluated during transient entrainment of atrial flutter by rapid high right atrial pacing in 5 of the 10 patients. In four of these five patients during such transient entrainment 1) one deflection of the double potential was captured with a relatively short activation time (mean interval 89 ± 45 ms) and the other deflection was captured with a relatively long activation time (mean interval 233 ± 24 ms), producing a paradoxical decrease in the short interdeflection interval from a mean of 75 ± 20 ms to a mean of 59 ± 24 ms; and 2) the configuration of the double potential remained similar to that observed during spontaneous atrial flutter. On pacing termination 1) the two double potential deflections were found to be associated with two different atrial flutter complexes in the electrocardiogram (ECG); 2) the previous double potential deflection relation resumed; and 3) when sinus rhythm was present, the double potentials were replaced by a broad, low amplitude electrogram recording at the same site. These functional double potentials probably represent collision of activation wave fronts in a functional center of the artial flutter reentrant circuit and therefore may serve as a marker for an area of functional block. In one of the five patients, double potentials were recorded from the site during transient entrainment of atrial flutter, during spontaneous atrial flutter and during sinus rhythm. These were called persistent double potentials and were associated with the same atrial flutter complex in the ECG, indicating that not all double potentials recorded during atrial flutter represent the same phenomenon

Comprehensive Management With the ABC (Atrial Fibrillation Better Care) Pathway in Clinically Complex Patients With Atrial Fibrillation: A Post Hoc Ancillary Analysis From the AFFIRM Trial

Background For patients with atrial fibrillation, a comprehensive care approach based on the Atrial fibrillation Better Care (ABC) pathway can reduce the occurrence of adverse outcomes. The aim of this paper was to investigate if an approach based on the ABC pathway is associated with a reduced risk of adverse events in "clinically complex" atrial fibrillation patients, including those with multiple comorbidities, polypharmacy, and prior hospitalizations. Methods and Results We performed a post hoc analysis of the AFFIRM (Atrial Fibrillation Follow-up Investigation of Rhythm Management) trial. The principal outcome was the composite of all-cause hospitalization and all-cause death. An integrated care approach (ABC group) was used in 3.8% of the multimorbidity group, 4.0% of the polypharmacy group, and 4.8%, of the hospitalized groups. In all "clinically complex" groups, the cumulative risk of the composite outcome was significantly lower in patients managed consistent with the ABC pathway versus non-ABC pathway-adherent (all P<0.05). Cox regression analysis showed a reduction of composite outcomes in ABC pathway-adherent versus non-ABC pathway-adherent for multimorbidity (hazard ratio [HR], 0.61, 95% CI, 0.44-0.85), polypharmacy (HR, 0.68, 95% CI, 0.47-1.00), and hospitalization (HR, 0.59, 95% CI, 0.42-0.85) groups. Secondary analyses showed that the higher number of ABC criteria fulfilled the larger associated reduction in relative risk, even for secondary outcomes considered. Conclusions Use of an ABC consistent pathway is associated with fewer major adverse events in patients with atrial fibrillation who have multiple comorbidities, use of polypharmacy, and prior hospitalization

Improved Outcomes by Integrated Care of Anticoagulated Patients with Atrial Fibrillation using the simple ABC (Atrial Fibrillation Better Care) Pathway

BACKGROUND: Integrated care for the clinical management of atrial fibrillation patients is advocated as a holistic way to improve outcomes; the simple Atrial fibrillation Better Care (ABC) pathway has been proposed. The ABC pathway streamlines care as follows: 'A' Avoid stroke; 'B' Better symptom management; 'C' Cardiovascular and Comorbidity optimization. METHODS: We performed a post hoc analysis of the Atrial Fibrillation Follow-Up Investigation of Rhythm Management (AFFIRM) trial. An 'integrated care' approach was defined according to the ABC pathway. Patients fulfilling all criteria were categorized as the 'ABC' group; those not fulfilling all criteria were the 'non-ABC' group. Trial-adjudicated all-cause death, composite outcome of stroke/major bleeding/cardiovascular death, and first hospitalization were the main study outcomes. RESULTS: Among the 4060 patients in the original cohort, 3169 (78%) had available data to compare integrated care (ABC; n\u202f=\u202f222; 7%) vs non-ABC (n\u202f=\u202f2947; 93%) management. Over a median follow-up of 3.7 (interquartile range, 2.8-4.6) years, atrial fibrillation patients managed with integrated care (ABC group) had lower rates for all study outcomes (all P &lt; .001) compared with the non-ABC group. A Cox multivariable regression analysis showed that atrial fibrillation patients managed in the ABC group had a significantly lower risk of all-cause death (hazard ratio [HR], 0.35; 95% confidence interval [CI], 0.17-0.75), composite outcome (HR, 0.35; 95% CI, 0.18-0.68), and first hospitalization (HR, 0.65; 95% CI, 0.53-0.80). CONCLUSIONS: The simple ABC pathway allows the streamlining of integrated care for atrial fibrillation patients in a holistic manner and is associated with a lower risk of adverse outcomes (including mortality, stroke/major bleeding/cardiovascular death, and hospitalization)

REDUCE-IT USA: Results From the 3146 Patients Randomized in the United States.

BackgroundSome trials have found that patients from the United States derive less benefit than patients enrolled outside the United States. This prespecified REDUCE-IT (Reduction of Cardiovascular Events with Icosapent Ethyl - Intervention Trial) subgroup analysis was conducted to determine the degree of benefit of icosapent ethyl in the United States.MethodsREDUCE-IT randomized 8179 statin-treated patients with qualifying triglycerides ≥135 and &lt;500 mg/dL and low-density lipoprotein cholesterol &gt;40 and ≤100 mg/dL and a history of atherosclerosis or diabetes mellitus to icosapent ethyl 4 g/d or placebo. The primary composite end point was cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, coronary revascularization, or hospitalization for unstable angina. The key secondary composite end point was cardiovascular death, nonfatal myocardial infarction, or nonfatal stroke. A hierarchy was prespecified for examination of individual and composite end points.ResultsA total of 3146 US patients (38.5% of the trial) were randomized and followed for a median of 4.9 years; 32.3% were women and 9.7% were Hispanic. The primary composite end point occurred in 24.7% of placebo-treated patients versus 18.2% of icosapent ethyl-treated patients (hazard ratio [HR], 0.69 [95% CI, 0.59-0.80]; P=0.000001); the key secondary composite end point occurred in 16.6% versus 12.1% (HR, 0.69 [95% CI, 0.57-0.83]; P=0.00008). All prespecified hierarchical end points were meaningfully and significantly reduced, including cardiovascular death (6.7% to 4.7%; HR, 0.66 [95% CI, 0.49-0.90]; P=0.007), myocardial infarction (8.8% to 6.7%; HR, 0.72 [95% CI, 0.56-0.93]; P=0.01), stroke (4.1% to 2.6%; HR, 0.63 [95% CI, 0.43-0.93]; P=0.02), and all-cause mortality (9.8% to 7.2%; HR, 0.70 [95% CI, 0.55-0.90]; P=0.004); for all-cause mortality in the US versus non-US patients, Pinteraction=0.02. Safety and tolerability findings were consistent with the full study cohort.ConclusionsWhereas the non-US subgroup showed significant reductions in the primary and key secondary end points, the US subgroup demonstrated particularly robust risk reductions across a variety of individual and composite end points, including all-cause mortality.Clinical trial registrationURL: https://www.clinicaltrials.gov. Unique identifier: NCT01492361

The effect of cardiac resynchronization without a defibrillator on morbidity and mortality: an individual patient data meta-analysis of COMPANION and CARE-HF

AIMS: Cardiac resynchronization therapy (CRT) reduces morbidity and mortality for patients with heart failure, reduced left ventricular ejection fraction, QRS duration >130 ms and in sinus rhythm. The aim of this study was to identify patient characteristics that predict the effect, specifically, of CRT pacemakers (CRT-P) on all-cause mortality or the composite of hospitalization for heart failure or all-cause mortality. METHODS AND RESULTS: We conducted an individual patient data meta-analysis of the Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure (COMPANION) and Cardiac Resynchronization-Heart Failure (CARE-HF) trials. Only patients assigned to CRT-P or control (n = 1738) were included in order to avoid confounding from concomitant defibrillator therapy. The influence of baseline characteristics on treatment effects was investigated. Median age was 67 (59-73) years, most patients were men (70%), 68% had a QRS duration of 150-199 ms and 80% had left bundle branch block. Patients assigned to CRT-P had lower rates for all-cause mortality (hazard ratio [HR] 0.68, 95% confidence interval [CI] 0.56-0.81; p < 0.0001) and the composite outcome (HR 0.67, 95% CI 0.58-0.78; p < 0.0001). No pre-specified characteristic, including sex, aetiology of ventricular dysfunction, QRS duration (within the studied range) or morphology or PR interval significantly influenced the effect of CRT-P on all-cause mortality or the composite outcome. However, CRT-P had a greater effect on the composite outcome for patients with lower body surface area and those prescribed beta-blockers. CONCLUSIONS: Cardiac resynchronization therapy-pacemaker reduces morbidity and mortality in appropriately selected patients with heart failure. Benefits may be greater in smaller patients and in those receiving beta-blockers. Neither QRS duration nor morphology independently predicted the benefit of CRT-P. CLINICAL TRIAL REGISTRATION: COMPANION, NCT00180258; CARE-HF, NCT00170300