Peter Santucci

Idiopathic Epicardial Left Ventricular Tachycardia Originating Remote From the Sinus of Valsalva Electrophysiological Characteristics, Catheter Ablation, and Identification From the 12-Lead Electrocardiogram

Background— Despite the success of catheter ablation for treatment of idiopathic ventricular tachycardia (VT), occasional patients have been reported in whom VT could not be ablated from the right or left ventricular endocardium or from the aortic sinus of Valsalva (ASOV). Methods and Results— In 12 of 138 patients (9%) with idiopathic VT referred for ablation, an epicardial left ventricular site of origin was identified >10 mm from the ASOV. Coronary venous mapping demonstrated epicardial preceding endocardial activation by >10 ms (41±7 versus 15±11 ms before QRS onset; P<0.001). VT induction was facilitated by catecholamines and terminated by adenosine. Ablation through the coronary veins or via percutaneous transpericardial catheterization was successful in 9 patients; 2 required direct surgical ablation as a result of anatomic constraints. No ECG pattern was specific for epicardial VT. However, slowed initial precordial QRS activation, as quantified by a novel metric, the maximum deflection index, was more useful. A delayed precordial maximum deflection index ≥0.55 identified epicardial VT remote from the ASOV with a sensitivity of 100% and a specificity of 98.7% relative to all other sites of origin (P<0.001). Conclusions— Although clinically underrecognized, idiopathic VT may originate from the perivascular sites on the left ventricular epicardium. The mechanism is consistent with triggered activity. It is amenable to ablation by transvenous or transpericardial approaches, although technical challenges remain. Recognition of a prolonged precordial maximum deflection index and early use of transvenous epicardial mapping are critical to avoid protracted and unsuccessful ablation elsewhere in the ventricles.

Pericardial Fat Is Independently Associated With Human Atrial Fibrillation

OBJECTIVES The purpose of this study was to investigate the association between atrial fibrillation (AF) and pericardial fat. BACKGROUND Pericardial fat is visceral adipose tissue that possesses inflammatory properties. Inflammation and obesity are associated with AF, but the relationship between AF and pericardial fat is unknown. METHODS Pericardial fat volume was measured using computed tomography in 273 patients: 76 patients in sinus rhythm, 126 patients with paroxysmal AF, and 71 patients with persistent AF. RESULTS Patients with AF had significantly more pericardial fat compared with patients in sinus rhythm (101.6 +/- 44.1 ml vs. 76.1 +/- 36.3 ml, p < 0.001). Pericardial fat volume was significantly larger in paroxysmal AF compared with the sinus rhythm group (93.9 +/- 39.1 ml vs. 76.1 +/- 36.3 ml, p = 0.02). Persistent AF patients had a significantly larger pericardial fat volume compared with paroxysmal AF (115.4 +/- 49.3 ml vs. 93.9 +/- 39.1 ml, p = 0.001). Pericardial fat volume was associated with paroxysmal AF (odds ratio: 1.11; 95% confidence interval: 1.01 to 1.23, p = 0.04) and persistent AF (odds ratio: 1.18, 95% confidence interval: 1.05 to 1.33, p = 0.004), and this association was completely independent of age, hypertension, sex, left atrial enlargement, valvular heart disease, left ventricular ejection fraction, diabetes mellitus, and body mass index. CONCLUSIONS Pericardial fat volume is highly associated with paroxysmal and persistent AF independent of traditional risk factors including left atrial enlargement. Whether pericardial fat plays a role in the pathogenesis of AF requires future investigation.

Predictors of Response to Cardiac Resynchronization Therapy in the Multicenter Automatic Defibrillator Implantation Trial With Cardiac Resynchronization Therapy (MADIT-CRT)

Background— We hypothesized that combined assessment of factors that are associated with favorable reverse remodeling after cardiac resynchronization-defibrillator therapy (CRT-D) can be used to predict clinical response to the device. Methods and Results— The study population comprised 1761 patients enrolled in the Multicenter Automatic Defibrillator Implantation Trial With Cardiac Resynchronization Therapy (MADIT-CRT). Best-subset regression analysis was performed to identify factors associated with echocardiographic response (defined as percent reduction in left ventricular end-diastolic volume 1 year after CRT-D implantation) and to create a response score. Cox proportional hazards regression analysis was used to evaluate the CRT-D versus defibrillator-only reduction in the risk of heart failure or death by the response score. Seven factors were identified as associated with echocardiographic response to CRT-D and made up the response score (female sex, nonischemic origin, left bundle-branch block, QRS ≥150 milliseconds, prior hospitalization for heart failure, left ventricular end-diastolic volume ≥125 mL/m2, and left atrial volume <40 mL/m2). Multivariate analysis showed a 13% (P<0.001) increase in the clinical benefit of CRT-D per 1-point increment in the response score (range, 0–14) and a significant direct correlation between risk reduction associated with CRT-D and response score quartiles: Patients in the first quartile did not derive a significant reduction in the risk of heart failure or death with CRT-D (hazard ratio=0.87; P=0.52); patients in the second and third quartiles derived 33% (P=0.04) and 36% (P=0.03) risk reductions, respectively; and patients in the upper quartile experienced a 69% (P<0.001) risk reduction (P for trend=0.005). Conclusion— Combined assessment of factors associated with reverse remodeling can be used for improved selection of patients for cardiac resynchronization therapy. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00180271.

Prospective Study of Atrial Fibrillation Termination During Ablation Guided by Automated Detection of Fractionated Electrograms

Introduction: Complex fractionated atrial electrograms (CFAE) may identify critical sites for perpetuation of atrial fibrillation (AF) and provide useful targets for ablation. Current assessment of CFAE is subjective; automated detection algorithms may improve reproducibility, but their utility in guiding ablation has not been tested.

The Effects of Statins and Renin-Angiotensin System Blockers on Atrial Fibrillation Recurrence Following Antral Pulmonary Vein Isolation

Introduction: Ablation has emerged as a major treatment option for atrial fibrillation (AF). However, this procedure is limited by a significant rate of AF recurrence. We aimed to examine the effects of statins, angiotensin‐converting enzyme inhibitors (ACE‐I), and angiotensin receptor blockers (ARB) on the recurrence rate of AF following ablation.

Endothelial dysfunction in heart failure identifies responders to cardiac resynchronization therapy

BACKGROUND The presence of endothelial dysfunction is associated with increased heart failure mortality. Cardiac resynchronization therapy (CRT) improves heart failure outcomes; however, current guidelines do not adequately identify responders to CRT. OBJECTIVE The purpose of this study was to determine whether endothelial dysfunction can predict response to CRT. METHODS Brachial artery flow-mediated dilation, a measure of endothelial function, was measured at baseline preimplant and 90 days postimplant in 33 patients undergoing CRT (age 64.2 +/- 16.8 years, left ventricular ejection fraction [LVEF] 25% +/- 9%, QRS duration 158 +/- 25 ms, New York Heart Association class III-IV). RESULTS Of the 33 patients, 19 (58%) were responders to CRT. Baseline flow-mediated dilation was 4.6% +/- 4.5% in responders and 8.6% +/- 4.2% in nonresponders (P <.01). After 90 days of CRT, responders had significant improvement in LVEF (23% +/- 8% to 30% +/- 9%, P = .03), 6-minute walk distance (756 +/- 213 feet to 1,089 +/- 242 feet, P = .04), and quality of life (52 +/- 22 to 31 +/- 28, P <.005), whereas nonresponders did not show improvement in these measures. The presence of baseline endothelial dysfunction correlated with impaired baseline functional capacity (r = 0.39, P = .03), and improvement in flow-mediated dilation correlated with improvement in 6-minute walk distance (r = 0.34, P = .05). Logistic regression analysis showed that every 1% reduction in baseline flow-mediated dilation correlated with an approximately 5% increased likelihood of response to CRT. The predictive value of baseline endothelial dysfunction was independent of QRS duration, LVEF, or dyssynchrony and provided additive prognostic value. CONCLUSION The presence of endothelial dysfunction independently identifies CRT responders and provides additive prognostic value for predicting response over current criteria. Addition of endothelial function assessment to current selection criteria may improve the ability to identify CRT responders.

Electroanatomic mapping of postpacing intervals clarifies the complete active circuit and variants in atrial flutter

BACKGROUND Typical atrial flutter is characterized by cavotricuspid isthmus dependence and activation sequentially around the tricuspid annulus (TA), usually counterclockwise. However, analysis of the upper portion of the annulus by postpacing interval after entrainment sometimes suggests it is outside the circuit. Details on the true active circuit are limited, particularly in the upper portions. OBJECTIVE The purpose of this study was to define the full active circuit in atrial flutter. METHODS In 26 patients with isthmus-dependent atrial flutter, we created detailed electroanatomic maps of postpacing intervals throughout the entire right atrium. Postpacing intervals within 20 ms of the flutter cycle length were defined as within the circuit. RESULTS Creating postpacing interval maps allowed characterization of the full active circuit in all patients, and revealed significant variations despite similar counterclockwise or clockwise patterns with activation mapping. In 8, the active circuit was solely around the TA. In 14, an oblique course between the anterior and posterior borders was found, with the upper circuit off the annulus, posterior to the right atrial appendage base. Of these, 8 coursed anterior to the SVC, 5 behind the SVC and 1 bifurcated the SVC. In 4 others, bifurcation of the upper circuit was seen around the right atrial appendage (n = 3), or around the combined right atrial appendage-superior vena cava (n = 1). CONCLUSION Despite similar activation around the TA, creating electroanatomic postpacing interval maps distinguishes the active flutter circuit from passively activated myocardium. Significant variability exists in the active circuit, with only a minority around the TA. Most commonly, the circuit courses not around a single barrier but obliquely between anterior and posterior borders.

Surface electrocardiographic patterns and electrophysiologic characteristics of atrial flutter following modified radiofrequency MAZE procedures.

Introduction: The radiofrequency MAZE is becoming a common adjunct to cardiac surgery in patients with atrial fibrillation. While a variety of postoperative arrhythmias have been described following the original Cox‐MAZE III procedure, the electrophysiological characteristics and surgical substrate of post‐radiofrequency MAZE flutter have not been correlated. We sought to determine the location, ECG patterns, and electrophysiological characteristics of post‐radiofrequency MAZE atrial flutter.

Electroanatomic Mapping of the Right Ventricle in a Patient with a Giant Epsilon Wave, Ventricular Tachycardia, and Cardiac Sarcoidosis

A 47‐year‐old man presented with sustained monomorphic ventricular tachycardia of right ventricular origin. Surface ECG recorded during sinus rhythm showed a bizarre “double QRS” pattern. Biventricular cardiomyopathy was found with predominant right ventricular involvement, due to cardiac sarcoidosis. Electroanatomic mapping was used to characterize the right ventricular substrate abnormalities and to decipher the specific activation abnormalities responsible for the ECG findings.

Electrophysiology Procedures Weighing the Factors Affecting Choice of Anesthesia

Invasive electrophysiologic procedures have evolved and increased in frequency significantly over the past 2 decades. The complexity and nature of the various procedures offered have also changed, and complex ablations for atrial fibrillation and ventricular tachycardia have become commonplace. These procedures often require the services of an anesthesiologist. An understanding of the specific nature and challenges of these procedures may be helpful in planning the optimal anesthetic and patient management. A paired review of these issues has been written from the standpoint of a practicing anesthesiologist. This review is written from the viewpoint of a cardiac electrophysiologist and will focus on the intra-procedural management of patients undergoing both cardiac implantable device implantation as well as catheter-based ablations, with a specific focus on the catheter ablation of atrial fibrillation. Ultimately, the proper management of these patients will facilitate successful procedural outcomes while maintaining a high degree of patient safety.