Francis Murgatroyd

2012 EHRA/HRS expert consensus statement on cardiac resynchronization therapy in heart failure: implant and follow-up recommendations and management

2012 EHRA/HRS expert consensus statement on cardiac resynchronization therapy in heart failure : implant and follow-up recommendations and management

Worldwide experience with a totally subcutaneous implantable defibrillator: early results from the EFFORTLESS S-ICD Registry

Aims The totally subcutaneous implantable-defibrillator (S-ICD) is a new alternative to the conventional transvenous ICD system to minimize intravascular lead complications. There are limited data describing the long-term performance of the S-ICD. This paper presents the first large international patient population collected as part of the EFFORTLESS S-ICD Registry. Methods and results The EFFORTLESS S-ICD Registry is a non-randomized, standard of care, multicentre Registry designed to collect long-term, system-related, clinical, and patient reported outcome data from S-ICD implanted patients since June 2009. Follow-up data are systematically collected over 60-month post-implant including Quality of Life. The study population of 472 patients of which 241 (51%) were enrolled prospectively has a mean follow-up duration of 558 days (range 13–1342 days, median 498 days), 72% male, mean age of 49 ± 18 years (range 9–88 years), 42% mean left ventricular ejection fraction. Complication-free rates were 97 and 94%, at 30 and 360 days, respectively. Three hundred and seventeen spontaneous episodes were recorded in 85 patients during the follow-up period. Of these episodes, 169 (53%) received therapy, 93 being for Ventricular Tachycardia/Fibrillation (VT/VF). One patient died of recurrent VF and severe bradycardia. Regarding discrete VT/VF episodes, first shock conversion efficacy was 88% with 100% overall successful clinical conversion after a maximum of five shocks. The 360-day inappropriate shock rate was 7% with the vast majority occurring for oversensing (62/73 episodes), primarily of cardiac signals (94% of oversensed episodes). Conclusion The first large cohort of real-world data from an International patient S-ICD population demonstrates appropriate system performance with clinical event rates and inappropriate shock rates comparable with those reported for conventional ICDs. Clinical trial registration URL: http://www.clinicaltrials.gov. Unique identifier NCT01085435.

Analysis of the cardiac rhythm preceding episodes of paroxysmal atrial fibrillation

AIMS This study seeks to elucidate whether there was a common mode of initiation of paroxysmal atrial fibrillation (PAF) episodes that might suggest new therapies. METHODS A library of 177 digitized and analyzed 24-hour Holter recordings from PAF pharmacotherapy trials was studied. All noise-free PAF episodes > or =0.5 minutes were identified. PAF episodes and the preceding 2 minutes of sinus rhythm were printed as tachograms and visually inspected. Heart rate and ectopic beat behavior were used to characterize modes of PAF onset by comparing half-minute segments of the final 2 minutes of sinus rhythm. RESULTS Thirty-four recordings (from 19 patients, aged 61.7 +/- 11.5 years) provided 231 PAF episodes suitable for analysis. No patients had a consistent mode of PAF onset. This was confirmed by systematic analysis of the five patients with the most episodes. Overall, a highly significant increase in ectopic beats, from 1.34 to 6.52 min(-1) (p < 0.001) was found, but heart rate did not significantly change (mean heart rate at onset = 64 beats/min). PAF was initiated by a solitary ectopic beat in more than half of the cases. No consistent evidence for short-long-short sequences, seen in ventricular arrhythmias, was found. CONCLUSION The mode of onset of atrial fibrillation is inconsistent, both across a population with PAF and within individuals. This has implications for understanding the mechanisms of atrial fibrillation onset in human beings and for the treatment of the disorder.

Real-time 3D echo in patient selection for cardiac resynchronization therapy.

OBJECTIVES this study investigated the use of 3-dimensional (3D) echo in quantifying left ventricular mechanical dyssynchrony (LVMD), its interhospital agreement, and potential impact on patient selection. BACKGROUND assessment of LVMD has been proposed as an improvement on conventional criteria in selecting patients for cardiac resynchronization therapy (CRT). Three-dimensional echo offers a reproducible assessment of left ventricular (LV) structure, function, and LVMD and may be useful in selecting patients for this intervention. METHODS we studied 187 patients at 2 institutions. Three-dimensional data from baseline and longest follow-up were quantified for volume, left ventricular ejection fraction (LVEF), and systolic dyssynchrony index (SDI). New York Heart Association (NYHA) functional class was assessed independently. Several outcomes from CRT were considered: 1) reduction in NYHA functional class; 2) 20% relative increase in LVEF; and 3) 15% reduction in LV end-systolic volume. Sixty-two cases were shared between institutions to analyze interhospital agreement. RESULTS there was excellent interhospital agreement for 3D-derived LV end-diastolic and end- systolic volumes, EF, and SDI (variability: 2.9%, 1%, 7.1%, and 7.6%, respectively). Reduction in NYHA functional class was found in 78.9% of patients. Relative improvement in LVEF of 20% was found in 68% of patients, but significant reduction in LV end-systolic volume was found in only 41.5%. The QRS duration was not predictive of any of the measures of outcome (area under the curve [AUC]: 0.52, 0.58, and 0.57 for NYHA functional class, LVEF, and LV end-systolic volume), whereas SDI was highly predictive of improvement in these parameters (AUC: 0.79, 0.86, and 0.66, respectively). For patients not fulfilling traditional selection criteria (atrial fibrillation, QRS duration <120 ms, or undergoing device upgrade), SDI had similar predictive value. A cutoff of 10.4% for SDI was found to have the highest accuracy for predicting improvement following CRT. CONCLUSIONS the LVMD quantification by 3D echo is reproducible between centers. SDI was an excellent predictor of response to CRT in this selected patient cohort and may be valuable in identifying a target population for CRT irrespective of QRS morphology and duration.

Low energy internal cardioversion of atrial fibrillation resistant to transthoracic shocks.

OBJECTIVE: To investigate the efficacy of internal cardioversion using low energy shocks delivered with a biatrial electrode configuration in chronic atrial fibrillation resistant to transthoracic shocks. METHODS: Low energy internal cardioversion was attempted in 11 patients who had been in atrial fibrillation for 233 (SD 193) days and had failed to cardiovert with transthoracic shocks of 360 J in both apex-base and anterior-posterior positions. Synchronised biphasic shocks of up to 400 V (approximately 6 J) were delivered, usually with intravenous sedation only, between high surface area electrodes in the right atrium and the left atrium (coronary sinus in nine, left pulmonary artery in one, left atrium via patent foramen ovale in one). RESULTS: Sinus rhythm was restored in 8/11 patients. The mean leading edge voltage of successful shocks was 363 (46) V [4.9 (1.2) J]. Higher energy shocks induced transient bradycardia [time to first R wave 1955 (218) ms]. No proarrhythmia or other acute complications were observed. CONCLUSIONS: Low energy internal cardioversion of atrial fibrillation can restore sinus rhythm in patients in whom conventional transthoracic shocks have failed.

Electrical cardioversion for AF-the state of the art.

Developments in ablation therapy and improved device technology have changed cardiac electrophysiology beyond recognition in the two decades. Atrial fibrillation (AF) is currently attracting particular interest, in part due to its increasing prevalence and thus its impact on healthcare resources,1–5 in part due to our greater understanding of its pathophysiology and particularly due to the recently realized potential for cure, at least in a proportion of patients.6 Intuitively, the restoration and maintenance of sinus rhythm would seem to be the ultimate goal of therapy; it had been assumed that this would improve patient symptomatology and prognosis. Recent studies, however, suggest that for many adequate thromboprophylaxis, rate control is at least as good as a rhythm control strategy.2,7–10 However, these studies focus on those over the age of 65 or those with thromboembolic risks and therefore are not necessarily applicable to those younger or the highly symptomatic. In these patients, a rhythm control strategy may be preferable; indeed where this strategy was successful in the AFFIRM study it was associated with improved prognosis.11 AF ablation also appears to be of prognostic benefit in some groups.12 Furthermore, in some cases, an identified precipitant (e.g., intoxication, thoracotomy) or an acute illness (e.g., thyrotoxicosis, pneumonia) precipitates an episode of sustained AF. In these patients, long-term maintenance of sinus rhythm seems achievable. For those with persistent AF, the first step in a rhythm control strategy is generally cardioversion. While chemical-induced cardioversion is sometimes possible, particularly with full loading with amiodarone,2,13 it is generally much less successful than electrical cardioversion, particularly if the arrhythmia has been present for more than 24

Myocardial tissue characterization by cardiac magnetic resonance imaging using T1 mapping predicts ventricular arrhythmia in ischemic and non-ischemic cardiomyopathy patients with implantable cardioverter-defibrillators

BACKGROUND Diffuse myocardial fibrosis may provide a substrate for the initiation and maintenance of ventricular arrhythmia. T1 mapping overcomes the limitations of the conventional delayed contrast-enhanced cardiac magnetic resonance (CE-CMR) imaging technique by allowing quantification of diffuse fibrosis. OBJECTIVE The purpose of this study was to assess whether myocardial tissue characterization using T1 mapping would predict ventricular arrhythmia in ischemic and non-ischemic cardiomyopathies. METHODS This was a prospective longitudinal study of consecutive patients receiving implantable cardioverter-defibrillators in a tertiary cardiac center. Participants underwent CMR myocardial tissue characterization using T1 mapping and conventional CE-CMR scar assessment before device implantation. The primary end point was an appropriate implantable cardioverter-defibrillator therapy or documented sustained ventricular arrhythmia. RESULTS One hundred thirty patients (71 ischemic and 59 non-ischemic) were included with a mean follow-up period of 430 ± 185 days (median 425 days; interquartile range 293 days). At follow-up, 23 patients (18%) experienced the primary end point. In multivariable-adjusted analyses, the following factors showed a significant association with the primary end point: secondary prevention (hazard ratio [HR] 1.70; 95% confidence interval [95% CI] 1.01-1.91), noncontrast T1(_native) for every 10-ms increment in value (HR 1.10; CI 1.04-1.16; 90-ms difference between the end point-positive and end point-negative groups), and Grayzone(_2sd-3sd) for every 1% left ventricular increment in value (HR 1.36; CI 1.15-1.61; 4% difference between the end point-positive and end point-negative groups). Other CE-CMR indices including Scar(_2sd), Scar(_FWHM), and Grayzone(_2sd-FWHM) were also significantly, even though less strongly, associated with the primary end point as compared with Grayzone(_2sd-3sd). CONCLUSION Quantitative myocardial tissue assessment using T1 mapping is an independent predictor of ventricular arrhythmia in both ischemic and non-ischemic cardiomyopathies.

Impact of prolonged implantable cardioverter-defibrillator arrhythmia detection times on outcomes: A meta-analysis

BACKGROUND Programming long arrhythmia detection times can reduce the incidence of implantable cardioverter-defibrillator (ICD) shock therapy. However, potential concerns exist regarding the impact on mortality and incidence of syncope. OBJECTIVE The purpose of this study was to perform a meta-analysis to better gauge the impact of prolonged arrhythmia detection times on the rates of ICD shock therapy and other adverse outcomes. METHODS Electronic databases were systematically searched. We included only prospective studies that examined the impact of programming longer vs shorter ICD arrhythmia detection times on clinical outcomes. Studies that were retrospective, did not have a control group, used historical controls, or did not specifically state the programmed detection times were excluded. Summary estimates of the relative risk (RR) of death, syncope, and appropriate and inappropriate shocks were calculated using random effects models. RESULTS Four studies enrolling 4896 patients were identified. During a mean/median follow-up of 12 to 17 months, there were 305 deaths, 106 patients experienced syncope, 264 received an appropriate shock, and 253 an inappropriate shock. In the long detection group there were significant reductions in mortality (RR 0.77, 95% confidence interval [CI] 0.62, 0.96), and inappropriate shocks (RR 0.50, 95% CI 0.39, 0.65), without significant increase in syncope (RR 1.23, 95% CI 0.84, 1.79). CONCLUSION Programming long arrhythmia detection times is an important strategy for improving outcomes from ICD therapy. The use of long detection times can significantly decrease the burden of inappropriate shock therapy and all-cause mortality in ICD recipients, without significant increase in syncope.

The impact of adjunctive complex fractionated atrial electrogram ablation and linear lesions on outcomes in persistent atrial fibrillation: a meta-analysis.

AIMS In persistent atrial fibrillation (PsAF), success rates for pulmonary vein isolation (PVI) alone are limited and additional substrate modification is often performed. The two most widely used substrate-based strategies are the ablation of complex fractionated atrial electrograms (CFAE) and left atrial linear ablation (LALA) at the roof and mitral isthmus. However, it is unclear whether adjunctive CFAE ablation or LALA add significant benefit to PVI alone. We performed a meta-analysis to better gauge the benefit of adjunctive CFAE ablation and LALA in PsAF. METHODS AND RESULTS Electronic databases were systematically searched. We included studies that examined the impact of CFAE ablation or LALA in addition to a PVI-based strategy on clinical outcomes in PsAF. We included both randomized and non-randomized studies. Totally 10 studies (n = 1821) were included: 6 evaluating CFAE ablation, 3 LALA, and 1 both approaches. In comparison with PVI alone, the addition of CFAE ablation [RR 0.86; 95% confidence intervals (CI) 0.64, 1.16; P = 0.32] or LALA (RR 0.64; 95% CI 0.37, 1.09; P = 0.10) offered no significant improvement in arrhythmia-free survival. However, adjunctive CFAE ablation was associated with significant increases (P < 0.05) and LALA non-significant increases in procedure and fluoroscopy times. CONCLUSION In PsAF, the addition of CFAE ablation or LALA, in comparison with PVI alone, offers no significant improvement in arrhythmia-free survival. Furthermore, they are associated with increases in both procedural and fluoroscopy times. The optimal ablation strategy for PsAF is currently unclear and needs further refinement.

A Multicenter Study of Shock Pathways for Subcutaneous Implantable Defibrillators

A purely subcutaneous implantable cardioverter defibrillator (ICD) requires higher energy but may be an effective alternative to transvenous ICDs to deliver lifesaving therapies.