Corrado Carbucicchio

Characterization of Left Ventricular Activation in Patients With Heart Failure and Left Bundle-Branch Block

Background—Conventional activation mapping in the dilated human left ventricle (LV) with left bundle-branch block (LBBB) morphology is incomplete given the limited number of recording sites that may be collected in a reasonable time and given the lack of precision in marking specific anatomic locations. Methods and Results—We studied LV activation sequences in 24 patients with heart failure and LBBB QRS morphology with simultaneous application of 3D contact and noncontact mapping during intrinsic rhythm and asynchronous pacing. Approximately one third of the patients with typical LBBB QRS morphology had normal transseptal activation time and a slightly prolonged or near-normal LV endocardial activation time. A “U-shaped” activation wave front was present in 23 patients because of a line of block that was located anteriorly (n=12), laterally (n=8), and inferiorly (n=3). Patients with a lateral line of block had significantly shorter QRS (P <0.003) and transseptal durations (P <0.001) and a longer distance from the LV breakthrough site to line of block (P <0.03). Functional behavior of the line of block was demonstrated by a change in its location during asynchronous ventricular pacing at different sites and cycle lengths. Conclusions—A U-shaped conduction pattern is imposed on the LV activation sequence by a transmural functional line of block located between the LV septum and the lateral wall with a prolonged activation time. Assessment of functional block is facilitated by noncontact mapping, which may be useful for identifying and targeting specific locations that are optimal for successful cardiac resynchronization therapy.

Perception of atrial fibrillation before and after radiofrequency catheter ablation: relevance of asymptomatic arrhythmia recurrence.

Background—The objective of this study was to assess the incidence and impact of asymptomatic arrhythmia in patients with highly symptomatic atrial fibrillation (AF) who qualified for radiofrequency (RF) catheter ablation. Methods and Results—In this prospective study, 114 patients with at least 3 documented AF episodes together with corresponding symptoms and an ineffective trial of at least 1 antiarrhythmic drug were selected for RF ablation. With the use of CARTO, circumferential lesions around the pulmonary veins and linear lesions at the roof of the left atrium and along the left atrial isthmus were placed. A continuous, 7-day, Holter session was recorded before ablation, right after ablation, and after 3, 6, and 12 months of follow-up. During each 7-day Holter monitoring, the patients recorded quality and duration of any complaints by using a detailed symptom log. More than 70 000 hours of ECG recording were analyzed. In the 7-day Holter records before ablation, 92 of 114 patients (81%) had documented AF episodes. All episodes were symptomatic in 35 patients (38%). In 52 patients (57%), both symptomatic and asymptomatic episodes were recorded, whereas in 5 patients (5%), all documented AF episodes were asymptomatic. After ablation, the percentage of patients with only asymptomatic AF recurrences increased to 37% (P<0.05) at the 6-month follow-up. An analysis of patient characteristics and arrhythmia patterns failed to identify a specific subset who were at high risk for the development of asymptomatic AF. Conclusions—Even in patients presenting with highly symptomatic AF, asymptomatic episodes may occur and significantly increase after catheter ablation. A symptom-only–based follow-up would substantially overestimate the success rate. Objective measures such as long-term Holter monitoring are needed to identify asymptomatic AF recurrences after ablation.

Endo-epicardial homogenization of the scar versus limited substrate ablation for the treatment of electrical storms in patients with ischemic cardiomyopathy.

OBJECTIVES This study investigated the impact on recurrences of 2 different substrate approaches for the treatment of these arrhythmias. BACKGROUND Catheter ablation of electrical storms (ES) for ventricular arrhythmias (VAs) has shown moderate long-term efficacy in patients with ischemic cardiomyopathy. METHODS Ninety-two consecutive patients (81% male, age 62 ± 13 years) with ischemic cardiomyopathy and ES underwent catheter ablation. Patients were treated either by confining the radiofrequency lesions to the endocardial surface with limited substrate ablation (Group 1, n = 49) or underwent endocardial and epicardial ablation of abnormal potentials within the scar (homogenization of the scar, Group 2, n = 43). Epicardial access was obtained in all Group 2 patients, whereas epicardial ablation was performed in 33% (14) of these patients. RESULTS Mean ejection fraction was 27 ± 5. During a mean follow-up of 25 ± 10 months, the VAs recurrence rate of any ventricular tachycardia (VTs) was 47% (23 of 49 patients) in Group 1 and 19% (8 of 43 patients) in Group 2 (log-rank p = 0.006). One patient in Group 1 and 1 patient in Group 2 died at follow-up for noncardiac reasons. CONCLUSIONS Our study demonstrates that ablation using endo-epicardial homogenization of the scar significantly increases freedom from VAs in ischemic cardiomyopathy patients.

Management of Ventricular Tachycardia in the Setting of a Dedicated Unit for the Treatment of Complex Ventricular Arrhythmias Long-Term Outcome After Ablation

Background— We investigated the impact of catheter ablation on ventricular tachycardia (VT) recurrence and survival in a large number of patients with structural heart disease treated in the setting of a dedicated multiskilled unit. Methods and Results— Since January 2007, we have implemented a multidisciplinary model, aiming for a comprehensive management of VT patients. Programmed ventricular stimulation was used to assess acute outcome. Primary end points were VT recurrence and the occurrence of cardiac and sudden cardiac death. Overall, 528 patients were treated by ablation (634 procedures; 1–4 procedures per patient). Among 482 tested with programmed ventricular stimulation after the last procedure, a class A result (noninducibility of any VT) was obtained in 371 patients (77%), class B (inducibility of nondocumented VT) in 12.4%, and class C (inducibility of index VT) in 10.6%. After a median follow-up time of 26 months, VT recurred in 164 (34.1%) of 472 patients. VT recurrence was documented in 28.6% of patients with a class A result versus 39.6% of patients with class B and 66.7% with class C result (log-rank P<0.001). The incidence of cardiac mortality was lower in class A patients than in those with class B and class C (8.4% versus 18.5% versus 22%, respectively; log-rank P=0.002). On the basis of multivariate analysis, postprocedural inducibility of index VT was independently associated both with VT recurrence (hazard ratio, 4.030; P<0.001) and with cardiac mortality (hazard ratio, 2.099; P=0.04). Conclusions— Within a dedicated VT unit, catheter ablation prevents long-term VT recurrences, which may favorably affect survival in a large number of patients who have VT.

Catheter ablation of ventricular tachycardia in remote myocardial infarction: substrate description guiding placement of individual linear lesions targeting noninducibility.

Introduction: The aim of this study was to describe the arrhythmogenic substrate in postinfarction patients with ventricular tachycardia (VT) guiding the placement of individual strategic linear lesions transecting all potential isthmuses using target area maps with limited mapping points to allow short procedure times.

Radiofrequency Ablation of Premature Ventricular Ectopy Improves the Efficacy of Cardiac Resynchronization Therapy in Nonresponders

OBJECTIVES This study sought to examine whether suppressing premature ventricular contractions (PVC) using radiofrequency ablation improves effectiveness of the cardiac resynchronization therapy (CRT) in nonresponders. BACKGROUND CRT is an effective strategy for drug refractory congestive heart failure. However, one-third of patients with CRT do not respond clinically, and the causes for nonresponse are poorly understood. Whether frequent PVC contribute to CRT nonresponse remains unknown. METHODS In this multicenter study, CRT nonresponders with >10,000 PVC in 24 h who underwent PVC ablation were enrolled from a prospective database. RESULTS Sixty-five subjects (age 66.6 ± 12.4 years, 78% men, QRS duration of 155 ± 18 ms) had radiofrequency ablation of PVC from 76 foci. Acute and long-term success rates of ablation were 91% and 88% in 12 ± 4 months of follow-up. There was significant improvement in left ventricular (LV) ejection fraction (26.2 ± 5.5% to 32.7 ± 6.7 %, p < 0.001), LV end-systolic diameter (5.93 ± 0.55 cm to 5.62 ± 0.32 cm, p < 0.001), LV end-diastolic diameter (6.83 ± 0.83 cm to 6.51 ± 0.91 cm, p < 0.001), LV end-systolic volume (178 ± 72 to 145 ± 23 ml, p < 0.001), LV end-diastolic volume (242 ± 85 ml to 212 ± 63 ml, p < 0.001), and median New York Heart Association functional class (3.0 to 2.0, p < 0.001). Modeling of pre-ablation PVC burden revealed an improvement in ejection fraction when the pre-ablation PVC burden was >22% in 24 h. CONCLUSIONS Frequent PVC is an uncommon yet significant cause of CRT nonresponse. Radiofrequency ablation of PVC foci improves LV function and New York Heart Association class and promotes reverse remodeling in CRT nonresponders. PVC ablation may be used to enhance CRT efficacy in nonresponders with significant PVC burden.

Long-term effectiveness of cardiac resynchronization therapy in heart failure patients with unfavorable cardiac veins anatomy comparison of surgical versus hemodynamic procedure.

OBJECTIVES This study sought to compare clinical, echocardiographic, and cardiopulmonary exercise testing response to cardiac resynchronization therapy (CRT) in patients with unfavorable anatomy of coronary sinus (CS) veins, randomized to transvenous versus surgical left ventricular (LV) lead implantation. BACKGROUND CRT efficacy depends on proper positioning of the LV lead over the posterolateral wall. A detailed pre-operative knowledge of CS anatomy might be of pivotal importance to accomplish a proper LV lead placement over this area. METHODS Study population included 40 patients (age 66 ± 4 years) with heart failure and indication to CRT, with unsuitable CS branches anatomy documented by pre-operative multislice computed cardiac tomography; 20 patients (Group 1) underwent surgical minithoracotomic LV lead implantation whereas 20 (Group 2) were implanted transvenously. New York Heart Association functional class, echocardiographic, and cardiopulmonary exercise testing data were assessed before and 1 year after CRT-system implant. RESULTS In all Group 1 patients, the LV leads were placed over the middle-basal segments of the posterolateral wall of the LV. This was not possible in Group 2 patients. One year after CRT, in Group 1, a significant improvement of New York Heart Association functional class, LV ejection fraction (from 28.8 ± 9.2% to 33.9 ± 7.2%, p < 0.01), LV end-systolic volume (from 165 ± 53 ml to 134 ± 48 ml, p < 0.001), and peak Vo(2)/kg (from 10.4 ± 4.5 ml/kg/min to 13.1 ± 3.1 ml/kg/min, p < 0.02) was observed. However, no improvement was observed in Group 2: LV ejection fraction varied from 27.4 ± 4.8% to 27.4 ± 5.7% (p = 0.9), LV end-systolic volume from 175 ± 46 ml to 166 ± 44 ml (p = 0.15), and peak Vo(2)/kg from 11.2 ± 3.2 ml/kg/min to 11.3 ± 3.4 ml/kg/min (p = 0.9). Changes after CRT between groups were highly significant. CONCLUSIONS In the setting of unfavorable CS branches of anatomy, CRT by a surgical minithoracotomic approach is preferable to transvenous lead implantation.

Radiofrequency ablation of atrioventricular junction and pacemaker implantation versus modulation of atrioventricular conduction in drug refractory atrial fibrillation

Modulation of atrioventricular (AV) node conduction and radiofrequency ablation of AV junction are alternative approaches to control ventricular rate in drug refractory atrial fibrillation (AF). In 2 centers, 120 patients were treated either with AV junction ablation (center 1, group 1, 60 patients [30 men, aged 64 +/- 11 years], paroxysmal AF in 24 patients) or with modulation (group 2, 60 patients [32 men, aged 58 +/- 12 years], paroxysmal AF in 43 patients). In group 1, complete AV block was achieved in all patients. In group 2, the procedure was performed in sinus rhythm (30 patients), prolonging the Wenckebach cycle length from 328 +/- 85 to 466 +/- 80 ms (p <0.01) or during AF (30 patients), decreasing ventricular rate from 178 +/- 35 to 96 +/- 35 beats/min (p <0.01), and to <100 beats/min in 17 patients (61%). Complete AV block was induced in 9 of 60 patients (15%). In groups 1 and 2, at a follow-up of 27 +/- 7 and 26 +/- 6 months, there were 2 deaths (1 cardiac, 1 sudden death) and 1 death for end-stage heart failure, respectively. Hospital readmissions decreased from 3.2 to 0.2 and from 4.2 to 0.2/year; late AF recurrences at of >120 beats/min were documented in 6% and 12%, respectively. Symptom score analysis including effort and rest dyspnea, exercise intolerance, weakness, and palpitation showed a significant improvement in both treatment groups, when acutely effective, in patients with paroxysmal and/or chronic AF. In conclusion, ablation of the AV junction shows a higher acute success rate compared with modulation of the AV node conduction in patients with drug refractory AF. Depending on the acute success, both approaches therefore were similarly effective in achieving long-term ventricular rate control and symptom score improvement.

Value of analysis of ST segment changes during tachycardia in determining type of narrow QRS complex tachycardia.

OBJECTIVES Repolarization changes during narrow QRS complex tachycardia were analyzed to differentiate the tachycardia mechanism and to guide the preliminary location of the accessory pathway. BACKGROUND Noninvasive determination of the mechanism of tachycardia is becoming increasingly important in view of the role of catheter ablation techniques for the cure of supraventricular tachycardia. METHODS We analyzed 159 12-lead electrocardiograms during narrow QRS complex tachycardia to evaluate 1) the tachycardia cycle; and 2) ST segment depression or T wave inversion, or both. Each patient underwent a complete electrophysiologic evaluation. RESULTS There were 13 atrial tachycardias, 57 atrioventricular (AV) node reentrant tachycardias and 89 AV reciprocating tachycardias. The mean RR cycle did not differ among types of tachycardia. ST segment depression >2 mm or T wave inversion, or both, was present more often in AV reciprocating tachycardia (57%) than in AV node tachycardia (25%). The magnitude of ST segment depression was greater in AV reciprocating tachycardia than in AV node tachycardia (mean +/- SD 1.3 +/- 1.6 vs. 0.7 +/- 0.8 mm, p < 0.005). In AV reciprocating tachycardia distinct patterns of repolarization changes and P wave configuration were associated with different sites of the accessory pathway. CONCLUSIONS The presence of ST segment depression >2 mm or T wave inversion, or both, during narrow QRS complex tachycardia suggests that AV reentry using an accessory pathway is the mechanism of the tachycardia. The phenomenon may be the consequence of a distinct pattern of retrograde atrial activation. Analysis of repolarization changes can guide preliminary localization of the accessory pathway even in the absence of ventricular preexcitation.

Fragmented and delayed electrograms within fibrofatty scar predict arrhythmic events in arrhythmogenic right ventricular cardiomyopathy: Results from a prospective risk stratification study

BACKGROUND Islets of myocytes within fibrofatty scars represent the substrate for reentrant ventricular arrhythmias in arrhythmogenic right ventricular cardiomyopathy (ARVC). Electroanatomic mapping can reliably identify such areas. OBJECTIVE To prospectively test the association between late and fragmented electrograms within scar and arrhythmic events in patients with ARVC. METHODS High-density right ventricle electroanatomic mapping was performed in 32 patients with ARVC without history of cardiac arrest or sustained ventricular arrhythmias. Standard definitions of electroanatomic scars and fragmented, isolated, and very late potentials were used. All patients received an implantable cardioverter-defibrillator for the primary prevention of sudden death. RESULTS After a mean follow-up of 25 ± 7 months, 12 (38%) patients received appropriate implantable cardioverter-defibrillator shock for sustained ventricular arrhythmias. With the exception of a higher rate of previous syncope (P = .053), patients with arrhythmic events at follow-up did not differ from those who remained free from arrhythmic events in terms of other clinical variables, including cardiac magnetic resonance findings. Electroanatomic scars were present in all patients. The distribution and extent of electroanatomic scars were similar in the 2 groups (38 ± 25 cm(2) vs 33 ± 20 cm(2); P = .51). However, patients with implantable cardioverter-defibrillator shock had a higher prevalence of fragmented electrograms (92% vs 20%; P <.001), of isolated late potentials (75% vs 20%; P = .004), and of very late potentials (67% vs 25%; P = .030). Fragmented electrograms were the only variable independently associated with arrhythmic events at follow-up (hazard ratio 21; P = .015). CONCLUSION The presence of fragmented and delayed electrograms within the scar predicts arrhythmic events in ARVC.