The outcome spectrum for Dilated Cardiomyopathy and Ventricular Tachycardia: results from the prospective, multicenter, DCM-VT ablation study

Funding Acknowledgements

Type of funding sources: Private company. Main funding source(s): The study was partially supported by an investigator initiated grant from Biosense Webster (a Johnson & Johnson company)

Background

Recurrent sustained ventricular tachycardia (VT) due to nonischemic dilated cardiomyopathy (DCM) is difficult to treat and long-term outcome data are limited.

Objective

We aimed to identify predictors for mortality or heart transplantation (MHT) and VT recurrence.

Methods

Consecutive DCM patients accepted for VT catheter ablation (RFCA) in 9 centers were prospectively enrolled and followed.

Results

Of 281 consecutive patients (age 60±13yrs, 85% men, LVEF 36±12%) 35% had VT storm, 20% incessant VT, and 68% failed amiodarone. During a median follow-up of 21 (IQR 6-30) months after RFCA (epicardial in 58%, no RFCA due to inaccessible target in 6.4%), 67(24%) patients died/underwent HT and 138(49%) had VT recurrence (45 within 30 days defined as early); the cumulative 4-year rate of VT or MHT was 70% and of MHT 38%.

In multivariable analysis predictors of MHT were early VT recurrence (HR 2.92 (CI1.37-6.21), p<0.01), amiodarone at discharge (HR 3.23 (CI1.43-7.33, p<0.01), renal dysfunction (HR 1.92 (CI1.01-3.64), p=0.046), and LVEF (HR 1.36 (CI 1.0-1.84), p=0.052). A LVEF ≤32% was the optimal threshold to identify patients at risk for MHT (AUC 0.75).

MHT per 100 person-years was 40.4 after early VT recurrence and significantly higher, compared to 14.2 after later VT recurrence and to 8.5 after RFCA with no VT recurrence (both p<0.01). Mortality rates for patients with VT recurrence after 30 days were not significantly higher than for patients with no VT recurrences

Patients with early recurrence and LVEF≤32% had a 1-year MHT rate of 55% (figure). VT recurrence was predicted by prior ICD shocks, basal antero-septal VT origin, and procedural failure but not LVEF.

Conclusion

DCM patients needing RFCA for VT are a high-risk group. Following RFCA half remain free of VT recurrences. Early VT recurrence with LVEF<0.32 identifies those with a very high risk and screening for mechanical support/ HT should be considered. Late VT recurrence after RFCA does not predict worse outcome.

The precordial R-prime wave: a novel discriminator between cardiac sarcoidosis and arrhythmogenic right ventricular cardiomyopathy in patients presenting with ventricular tachycardia

Funding Acknowledgements

Type of funding sources: Other. Main funding source(s): The department of cardiology from Leiden University Medical Center receives unrestricted grants from Edwards Lifesciences, Biotronik, Medtronik, Boston Scientific and BioSense Webster. MS was supported by the Research Fellowship of the European Society of Cardiology 2017/2018.

Background Cardiac sarcoidosis (CS) with right ventricular (RV) involvement may mimic ARVC. Histopathological differences may result in disease specific RV activation patterns, detectable on the 12-lead electrocardiogram (ECG). Scar in ARVC progresses from epicardium to endocardium and may lead to delayed activation of areas with reduced voltages, translating into terminal activation delay and occasionally an (epsilon) wave with small amplitude on the ECG. On the contrary, patchy transmural RV scar in CS may lead to conduction block, and therefore late activated areas with preserved voltages, reflected as preserved R’-waves in the right precordial leads.

Purpose To determine whether the terminal activation patterns in precordial leads V1-V3 distinguish CS with RV involvement from ARVC.

Methods This is a multicenter retrospective study including patients with either 1) CS with RV involvement or 2) gene-positive ARVC referred for VT ablation. A non-ventricular paced 12-lead surface ECG prior to ablation was obtained (25mm/s and 10mm/mV). For detailed analysis, Leiden ECG Analysis and Decomposition Software (LEADS) was used. After detection of QRST complexes in the spatial velocity signal, LEADS generates a representative and low-noise averaged beat. Then, measurements per lead were performed using the measurement tool in Adobe Pro DC. Based on the hypothesis that conduction block in CS will lead to late activated areas with preserved voltages, we measured the surface area (SA) of the R’-wave in V1-V3. An R’-wave was defined as any positive deflection from baseline after an S-wave.

Results 13 CS patients with RV involvement (54 ± 8years, 62% male) and 23 ARVC patients (37 ± 15years, 78% male) were included. A R’-wave in V1-V3 was present in all CS patients, compared to 11 (48%) of ARVC patients (p = 0.002). The maximum R’-wave SA in lead V1-V3 was 3.55 (IQR:2.18-5.81) mm2 in CS vs. 0.00 (IQR:0.00-0.43) mm2 in ARVC (p < 0.001; Figure A). By ROC-analysis, the maximum R’-wave SA in lead V1-V3 was an excellent discriminator (area under the curve 0.980 [95%CI: 0.945-1.000]). A cutoff of ≥1.65mm2 had a sensitivity of 85% and specificity of 96% for diagnosing CS. An algorithm was created including the presence of an R’-wave in V1-V3 and the SA of this R’-wave (Figure B). This was validated in a second cohort (18 CS and 40 ARVC) with 72% sensitivity and 88% specificity.

Conclusion Transmural RV scars in CS may cause localized conduction block, leading to late activated areas with preserved voltages, reflected as large R’-wave on the 12-lead surface ECG. An easily applicable algorithm including the surface area of the largest R’-wave in lead V1-V3 ≥1.65mm2 distinguishes CS from ARVC with good sensitivity and specificity. The QRS terminal activation in precordial leads V1-V2 may reflect disease specific scar patterns (for examples: Figure C). Abstract Figure

Ventricular mapping during atrial and ventricular pacing. Relationship of multipotential electrograms to ventricular tachycardia reentry circuits after myocardial infarction

AIMS

Conduction through separated myocyte bundles causes multipotential electrograms and reentrant ventricular tachycardia. We hypothesized that without initiating tachycardia, the reentry region could be detected by analysing the change in multipotential electrograms during two different activation sequences.

METHODS AND RESULTS

During catheter mapping and ablation in 16 patients with ventricular tachycardia late after infarction ventricular electrograms were recorded from 1072 sites during atrial and right ventricular paced ventricular activation. Multipotential electrograms were present during both activation sequences at 285 (27%) sites, during atrial pacing only at 159 (15%) sites and during right ventricular pacing only at 152 (14%) sites. Sites with multipotential electrograms during both activation sequences were more often related to a ventricular tachycardia circuit isthmus (43%) as compared to sites where such electrograms were present during one activation sequence (20%). Multipotential electrograms with >2 low amplitude deflections and a >100 ms difference in duration between the two activation sequences were infrequent but highly predictive of the reentry circuit.

CONCLUSION

Regions with fixed multipotentials consistent with conduction block might be useful guides for ablation approaches that target large regions of the infarct, but are not sufficiently specific to be the sole guide for focal ablation approaches.

Atrial fibrillation after cardiac surgery

PURPOSE

To review the epidemiology, mechanisms, complications, predictors, prevention, and treatment of atrial fibrillation following cardiac surgery.

DATA SOURCES

MEDLINE search of English-language reports published between 1966 and 2000 and a search of references of relevant papers.

STUDY SELECTION

Clinical and basic research studies on atrial fibrillation after cardiac surgery.

DATA EXTRACTION

Relevant clinical information was extracted from selected articles.

DATA SYNTHESIS

Atrial fibrillation occurs in 10% to 65% of patients after cardiac surgery, usually on the second or third postoperative day. Postoperative atrial fibrillation is associated with increased morbidity and mortality and longer, more expensive hospital stays. Prophylactic use of beta-adrenergic blockers reduces the incidence of postoperative atrial fibrillation and should be administered before and after cardiac surgery to all patients without contraindication. Prophylactic amiodarone and atrial overdrive pacing should be considered in patients at high risk for postoperative atrial fibrillation (for example, patients with previous atrial fibrillation or mitral valve surgery). For patients who develop atrial fibrillation after cardiac surgery, a strategy of rhythm management or rate management should be selected. For patients who are hemodynamically unstable or highly symptomatic or who have a contraindication to anticoagulation, rhythm management with electrical cardioversion, amiodarone, or both is preferred. Treatment of the remaining patients should focus on rate control because most will spontaneously revert to sinus rhythm within 6 weeks after discharge. All patients with atrial fibrillation persisting for more than 24 to 48 hours and without contraindication should receive anticoagulation.

CONCLUSIONS

Atrial fibrillation frequently complicates cardiac surgery. Many cases can be prevented with appropriate prophylactic therapy. A strategy of rhythm management for symptomatic patients and rate management for all other patients usually results in reversion to sinus rhythm within 6 weeks of discharge.

Electrophysiology and anatomic characterization of an epicardial accessory pathway

Pericardial access permitted epicardial catheter mapping and ablation of a rapidly conducting posteroseptal accessory pathway (AP) that had failed repeated ablation attempts. Transient block was achieved at the site of an AP potential. The AP was visible at surgery and resected. Histologic examination revealed cells typical of specialized cardiac conduction tissue. The location, size, and presence of conduction tissue likely account for failure of catheter ablation and resistance to drug therapy.

Implantable cardioverter defibrillators in heart failure

Implantable cardioverter defibrillators provide effective and reliable treatment of spontaneous VT and VF. These devices can be expected to decrease the risk for arrhythmic death in patients with heart failure but do not improve overall survival when death from severe pump dysfunction is imminent. Appropriate patient selection is a major aspect of arrhythmia management. Future devices will incorporate features that have the potential to reduce atrial arrhythmias, improve ventricular function, monitor hemodynamics, and prevent sudden arrhythmic death.

Recalls and safety alerts involving pacemakers and implantable cardioverter-defibrillator generators

CONTEXT

Unanticipated pacemaker and implantable cardioverter-defibrillator (ICD) generator malfunctions sometimes warrant recall by the US Food and Drug Administration (FDA). Despite increasingly frequent device implantation, pacemaker and ICD recalls and safety alerts (advisories) remain poorly characterized.

OBJECTIVES

To determine pacemaker and ICD generator advisory rates in the United States, to identify trends in these rates, and to examine their clinical and financial implications.

DESIGN AND SETTING

Analysis of weekly FDA Enforcement Reports issued between January 1990 and December 2000 to identify all advisories involving pacemaker or ICD generators in the United States. Recalls and safety alerts involving lead malfunctions were not included.

MAIN OUTCOME MEASURES

Number of pacemakers and ICD generators in the United States subject to FDA recall or safety alert in 1990-2000; annual pacemaker and ICD advisory rates in the United States in 1990-2000; and estimated cost of device advisories.

RESULTS

During the study period, 52 advisories (median [25th and 75th percentiles], 4 [4 and 7] per year) involving 408 500 pacemakers and 114 645 ICDs (523 145 total devices) were issued. Hardware malfunctions (35 advisories affecting 280 641 devices) and computer errors (10 advisories affecting 216 533 devices) accounted for 95% of device recalls. Implantable cardioverter-defibrillators were recalled more frequently than pacemakers (mean [SD], 16.4 [1.6] vs 6.7 [0.8] advisories per 100 person-years; P<.001). Between 1995 and 2000, the annual advisory rate increased for both pacemakers (P for trend <.001) and ICDs (P for trend =.02). An estimated 1.3 million device checks and analyses and 36 187 device replacements resulted from the advisories and cost approximately $870 million.

CONCLUSIONS

Pacemaker and ICD recalls and safety alerts occur frequently, affect many patients, and appear to be increasing in number and rate. With the growing number of device implants and expanding indications for device therapy, the number of patients affected by device advisories will likely continue to increase.

Catheter ablation in patients with multiple and unstable ventricular tachycardias after myocardial infarction: short ablation lines guided by reentry circuit isthmuses and sinus rhythm mapping

BACKGROUND

Extensive lines of radiofrequency (RF) lesions through infarct (MI) can ablate multiple and unstable ventricular tachycardias (VTs). Methods for guiding ablation that minimize unnecessary RF applications are needed. This study assesses the feasibility of guiding RF line placement by mapping to identify a reentry circuit isthmus.

METHODS AND RESULTS

Catheter mapping and ablation were performed in 40 patients (MI location: inferior, 28; anterior, 7; and both, 5) with an electroanatomic mapping system to measure the infarct region and ablation lines. The initial line was placed in the MI region either through a circuit isthmus identified from entrainment mapping or a target identified from pace mapping. A total of 143 VTs (42 stable, 101 unstable) were induced. An isthmus was identified in 25 patients (63%; 5 with only stable VTs, 5 with only unstable VTs, and 15 with both VTs). Inducible VTs were abolished or modified in 100% of patients when the RF line included an isthmus compared with 53% when RF had to be guided by pace mapping (P=0.0002); those with an isthmus identified received shorter ablation lines (4.9+/-2.4 versus 7.4+/-4.3 cm total length, P=0.02). During follow-up, spontaneous VT decreased markedly regardless of whether an isthmus was identified. VT stability and number of morphologies did not influence outcome.

CONCLUSIONS

A 4- to 5-cm line of RF lesions abolishes all inducible VTs in more than 50% of patients. Less ablation is required if a reentry circuit isthmus is identified even when multiple and unstable VTs are present.

Multi atrial maco-re-entry circuits in adults with repaired congenital heart disease: entrainment mapping combined with three-dimensional electroanatomic mapping

OBJECTIVES

We sought to characterize re-entry circuits causing intra-atrial re-entrant tachycardias (IARTs) late after the repair of congenital heart disease (CHD) and to define an approach for mapping and ablation, combining anatomy, activation sequence data and entrainment mapping.

BACKGROUND

The development of IARTs after repair of CHD is difficult to manage and ablate due to complex anatomy, variable re-entry circuit locations and the frequent co-existence of multiple circuits.

METHODS

Forty-seven re-entry circuits were mapped in 20 patients with recurrent IARTs refractory to medical therapy. In the first group (n = 7), ablation was guided by entrainment mapping. In the second group (n = 13), entrainment mapping was combined with a three-dimensional electroanatomic mapping system to precisely localize the scar-related boundaries of re-entry circuits and to reconstruct the activation pattern.

RESULTS

Three types of right atrial macro-re-entrant circuits were identified: those related to a lateral right atriotomy scar (19 IARTs), the Eustachian isthmus (18 IARTs) or an atrial septal patch (8 IARTs). Two IARTs originated in the left atrium. Radiofrequency (RF) lesions were applied to transect critical isthmuses in the right atrium. In three patients, the combined mapping approach identified a narrow isthmuses in the lateral atrium, where the first RF lesion interrupted the circuit; the remaining circuits were interrupted by a series of RF lesions across a broader path. Overall, 38 (81%) of 47 IARTs were successfully ablated. During follow-up ranging from 3 to 46 months, 16 (80%) of 20 patients remained free of recurrence. Success was similar in the first 7 (group 1) and last 13 patients (group 2), but fluoroscopy time decreased from 60 +/- 30 to 24 +/- 9 min/procedure, probably related to the increasing experience and ability to monitor catheter position non-fluoroscopically.

CONCLUSIONS

Entrainment mapping combined with three-dimensional electroanatomic mapping allows delineation of complex re-entry circuits and critical isthmuses as targets for ablation. Radiofrequency catheter ablation is a reasonable option for treatment of IARTs related to repair of CHD.

Saline-cooled versus standard radiofrequency catheter ablation for infarct-related ventricular tachycardias

BACKGROUND

Saline cooling of the electrode during radiofrequency (RF) ablation increases lesion size in animal models. If cooled RF also increases lesion size in human infarcts, it should facilitate the termination of ventricular tachycardia (VT).

METHODS AND RESULTS

In 66 patients with VT due to prior infarction, 366 ablation sites, which were classified by entrainment and isolated potentials followed by ablation during VT with either standard RF energy (247 sites) or cooled RF (119 sites), were retrospectively reviewed to compare the efficacy for terminating VT. RF energy was applied at 259 isthmus sites, 62 bystander sites, 28 inner loop sites, and 17 outer loop sites. Compared with standard RF, cooled RF terminated VT more frequently at isthmus sites where an isolated potential was present (89% versus 54%, P=0.003), isthmus sites without an isolated potential (36% versus 21%, P=0.04), and at inner loop sites (60% versus 22%, P=0.04). Termination rates were similarly low for cooled and standard RF at bystander sites (14% versus 9%, P=0.56) and outer loop sites (13% versus 11%, P=0.93).

CONCLUSIONS

Greater efficacy of cooled RF for terminating VT is consistent with the production of a larger lesion in human infarctions, which should facilitate successful ablation.

The N + 1 difference: a new measure for entrainment mapping

OBJECTIVES

The purpose of this study was to develop and test a new entrainment mapping measurement, the N + 1 difference.

BACKGROUND

Entrainment mapping is useful for identifying re-entry circuit sites but is often limited by difficulty in assessing: 1) changes in QRS complexes or P-waves that indicate fusion, and 2) the postpacing interval (PPI) recorded directly from the stimulation site.

METHODS

In computer simulations of re-entry circuits, the interval from a stimulus that reset tachycardia to a timing reference during the second beat after the stimulus was compared with the timing of local activation at the site during tachycardia to define an interval designated the N + 1 difference. The N + 1 difference was compared with the PPI-tachycardia cycle length (TCL) difference in simulations and at 65 sites in 10 consecutive patients with ventricular tachycardia (VT) after myocardial infarction and at 45 sites in 10 consecutive patients with atrial flutter.

RESULTS

In simulations, the N + 1 difference was equal to the PPI-TCL difference. During mapping of VT and atrial flutter, the N + 1 difference correlated well with the PPI-TCL difference (r > or = 0.91, p < 0.0001), identifying re-entry circuit sites with sensitivity of > or = 86% and specificity of > or = 90%. Accuracy was similar using either the surface electrocardiogram or an intracardiac electrogram (Eg) as the timing reference.

CONCLUSIONS

The N + 1 difference allows entrainment mapping to be used to identify re-entry circuit sites when it is difficult to evaluate Egs at the mapping site or fusion in the surface electrocardiogram.

Single catheter determination of local electrogram prematurity using simultaneous unipolar and bipolar recordings to replace the surface ECG as a timing reference

Bipolar recordings eliminate much of the far-field signal, while minimally filtered unipolar recordings contain substantial far-field signal components. These properties may allow the onset of the unipolar recording to serve as a timing reference for the bipolar recording obtained from the same electrode catheter during mapping of focal atrial or ventricular tachycardias. Mapping and RF ablation were performed in 26 patients with focal ventricular tachycardia and 14 patients with focal atrial tachycardia. At 205 mapping sites, simultaneous recordings of (1) minimally filtered unipolar electrograms (0.5-500 Hz), (2) high pass filtered unipolar electrograms (100 Hz), and (3) filtered bipolar recordings (30-500 Hz) were analyzed. The interval between the onset of the minimally filtered unipolar electrogram and the first peak of the bipolar electrogram (UniOn-BiP) correlated closely with the timing of the local electrogram referenced to the surface ECG (r = 0.85, P < 0.001). Of 53 sites where RF ablation was performed, UniOn-BiP was shorter at successful compared to unsuccessful sites (3.8 +/- 3.5 vs 9.2 +/- 5.2 ms, P < 0.001) and was < 15 ms at all successful sites. In conclusion, the comparison of simultaneous unipolar and bipolar electrograms from a single catheter allows assessment of the prematurity of local electrograms from a focal source without the use of the P wave or QRS onset as a timing reference.

Strategies for catheter ablation of scar-related ventricular tachycardia

Ventricular tachycardia (VT) due to reentry in and around regions of ventricular scar from an old myocardial infarction or cardiomyopathic process is often a difficult management problem. Radiofrequency catheter ablation is an option for controlling frequent VT episodes. Patient and VT characteristics determine the mapping and ablation approach and efficacy. In patients with a VT that is hemodynamically tolerated to allow mapping, prevention of recurrent VT is achieved in 54% to 66% of patients with a procedure related mortality of 1% to 2.7%. Multiple morphologies of monomorphic VT and circuits that are located deep to the endocardium are common problems that reduce efficacy. Mapping to identify target regions for ablation can be difficult if VT is rapid and not tolerated, or not inducible. Ablation of these "unmappable VTs" by designing ablation lines or areas based on the characteristics of the scar as assessed during sinus rhythm, and using approaches to assess global activation from a limited number of beats has been shown to be feasible. Ablation of multiple VTs, epicardial VTs, and poorly tolerated VTs are feasible. Future studies defining efficacy and risks are needed.

Identification of left atrial origin of ectopic tachycardia during right atrial mapping: analysis of double potentials at the posteromedial right atrium

INTRODUCTION

The high posteromedial right atrium is adjacent to the left atrium near the right superior pulmonary vein. We hypothesized that analysis of electrograms at this site could distinguish left from right atrial tachycardia.

METHODS AND RESULTS

Atrial mapping was performed in 16 patients with left atrial origin ectopic tachycardia (11 patients with right superior pulmonary vein origin and 5 patients with other left atrial tachycardias). During left atrial tachycardia, earliest right atrial activation was recorded at the high posterior right atrium in 14 of 16 patients. At all of these 14 early sites, double potentials were recorded during tachycardia. The first potential was a far-field signal from left atrium as indicated by the following: (1) during sinus beats, the timing of the two potentials reversed such that the left atrial one was late; (2) ablation at the right atrial site did not decrease the amplitude of the first potential, but did decrease the amplitude of the second potential; and (3) the timing of activation at the adjacent left atrium agreed with that of the first potential. In the 11 right superior pulmonary vein tachycardias, the first potential was markedly earlier than the p wave onset, but in left atrial tachycardias with other origins it was later. In a control group of six patients with pacing to simulate right atrial tachycardia, double potentials were recorded in the posterior right atrium, but the timing of components did not reverse during sinus rhythm.

CONCLUSION

For some left atrial ectopic tachycardias, particularly those originating from the right superior pulmonary vein, recognition of left versus right atrial origin can be accomplished during right atrial mapping by analysis of double potentials in the posteromedial right atrium.

Early outcome of initiating amiodarone for atrial fibrillation in advanced heart failure

BACKGROUND

Little information exists about the early outcomes of initiating amiodarone for atrial fibrillation in patients with advanced heart failure. This study assessed the initial rate of success and complications of amiodarone therapy initiated for patients with atrial fibrillation during hospitalization for heart failure.

METHODS

We reviewed medical records for 37 consecutive patients with left ventricular ejection fractions </=40% who underwent initiation of amiodarone for atrial fibrillation during hospitalization on a heart failure service.

RESULTS

Atrial fibrillation was present in 35 (95%) and atrial flutter in 2 (5%), with mean duration of 30 months. New York Heart Association class was 3.1 (+/-1.1). Left ventricular ejection fraction was 24% +/- 7%. All patients had received oral amiodarone with an initial dose of 1.2 +/- 0.2 g/day. Bradyarrhythmia led to discontinuation of digoxin in 12 (32%) patients and to permanent pacemaker placement in 7 (19%) patients. Conversion to sinus rhythm occurred spontaneously in 2 patients and after electrical cardioversion in 26 patients, for an initial success of 76%. After a median follow-up of 9.5 months, 21 of 37 (57%) patients remained in sinus or atrial-paced rhythm. Amiodarone complications occurred after discharge in 5 (14%) patients, 4 with hypothyroidism.

CONCLUSIONS

Amiodarone with electrical cardioversion has a high initial success rate for treatment of atrial fibrillation in patients with heart failure with advanced systolic dysfunction. The major early side effect was bradyarrhythmia, frequently requiring discontinuation of digoxin or permanent pacemaker placement.

Catheter ablation for hemodynamically unstable monomorphic ventricular tachycardia

INTRODUCTION

Hemodynamic collapse precludes extensive catheter mapping to identify focal target regions in many patients with ventricular tachycardia (VT) associated with heart disease. This study tested the feasibility of catheter ablation of poorly tolerated VTs by targeting a region identified during sinus rhythm.

METHODS AND RESULTS

Ablation was attempted in five patients, ages 44 to 59 years, with left ventricular ejection fractions of 0.15 to 0.20 and poorly tolerated VT causing multiple implantable defibrillator therapies (6 to 30 episodes/month). VT was due to prior infarction in three patients and nonischemic cardiomyopathy in two. Target regions were sought that met the following criteria: (1) evidence of slow conduction from fractionated sinus rhythm electrograms and stimulus-QRS delays during pace mapping, and (2) evidence that the region contains the reentrant circuit exit from pace mapping. In 4 of 5 patients, a target region was identified and radiofrequency lesions applied. Ablation abolished all recurrences of VT in 3 of 4 patients during follow-up of 14 to 22 months. There were no complications.

CONCLUSION

Ablation of poorly tolerated VT is feasible in some patients by mapping during sinus rhythm and performing ablation over a region of identifiable scar that contains abnormal conduction and a presumptive VT exit.

Mapping and radiofrequency catheter ablation of the three types of sustained monomorphic ventricular tachycardia in nonischemic heart disease

INTRODUCTION

Sustained monomorphic ventricular tachycardia (VT) associated with nonischemic cardiomyopathy (CMP) is uncommon. Optimal approaches to catheter mapping and ablation are not well characterized, but they are likely to depend on the VT mechanism. The purpose of this study was to evaluate the mechanisms of sustained monomorphic VT encountered in nonischemic CMP and to assess the feasibility, safety, and efficacy of catheter radiofrequency ablation for treatment.

METHODS AND RESULTS

Twenty-six consecutive patients with nonischemic CMP referred for management of recurrent VT were studied. In 16 (62%) patients, VT was related to a region of abnormal electrograms consistent with scar and the response to pacing suggested a reentrant mechanism. In 5 (19%) patients, VT was due to bundle branch or interfascicular reentry. In 7 (27%) patients, the VT mechanism was focal automaticity, 4 of whom had evidence of tachycardia-induced CMP. After catheter ablation targeting parts of reentrant circuits, VT was not inducible in 8 (53%) of 15 patients with scar-related reentry, was modified in 5 (33%) patients, and still was inducible in 2 (13%) patients. Ablation was successful in 5 of 5 patients with bundle branch reentry and in 6 of 7 patients with a focal automaticity mechanism. Overall, catheter ablation abolished clinical recurrence of VT in 20 (77%) of 26 patients during a follow-up of 15 +/- 12 months.

CONCLUSION

Three different mechanisms of VT are encountered in patients with nonischemic CMP. The mapping and ablation approach varies with the type of VT. In this selected population, the overall efficacy was 77%.

DDD-pacing-induced cardiomyopathy following AV node ablation for persistent atrial tachycardia

Ventricular rate control by catheter ablation of the AV node and pacing in patients with persistent atrial tachycardia has been reported to improve left ventricular function. However, this approach requires careful selection of the pacing mode. We report a patient who underwent AV node ablation for persistent multiple atrial tachycardias, and who then had a non-mode-switching pacemaker implanted. Because of an inappropriately programmed relatively high upper rate limit, the patient developed left ventricular dysfunction after 6 years. This resolved after programming the pacemaker to VVI at 70 bpm.

Characteristics of electrograms recorded at reentry circuit sites and bystanders during ventricular tachycardia after myocardial infarction

OBJECTIVES

The purpose of this study was to determine the relation of isolated potentials (IPs) recorded during ventricular tachycardia (VT) to reentry circuit sites identified by entrainment.

BACKGROUND

Reentry circuits causing VT late after myocardial infarction are complex. Both IPs and entrainment have been useful for identifying successful ablation sites, but the relation of IPs to the location in the reentry circuit as determined by entrainment has not been completely defined.

METHODS

Data from catheter mapping of 70 monomorphic VTs in 36 patients with prior myocardial infarction were retrospectively analyzed. Entrainment followed by radiofrequency current (RF) ablation was performed at 384 sites. On the basis of entrainment, sites were classified as reentry circuit exit, central-proximal, inner or outer loop sites. Sites outside the circuit were divided into remote and adjacent bystanders.

RESULTS

Isolated potentials were recorded at 50% (51 of 101) of reentry circuit exit, central and proximal sites as compared with only 8% (11 of 146, p < 0.001) of inner loop and outer loop sites and only 1.8% (2 of 106) of remote bystander sites (p < 0.001). Isolated potentials were also present at 45% of adjacent bystander sites. At central and proximal sites the presence of an IP increased the incidence of tachycardia termination by RF to 47.5% from 24% (p = 0.05). At exit sites tachycardia termination occurred frequently regardless of the presence or absence of IPs (45% vs. 48%, p = NS). Isolated potentials at exit, central and proximal sites had a shorter duration at sites where ablation terminated VT than at sites without termination (20.9 +/- 9.6 ms vs. 35.7 +/- 15.3 ms, p < 0.001).

CONCLUSIONS

Isolated potentials are a useful guide to sites in the central-proximal region of the reentry circuit, but often fail to identify exit sites where ablation is successful. Entrainment and analysis of electrograms provide complementary information during mapping of VT.

Ablation of ventricular tachycardia with a saline-cooled radiofrequency catheter: anatomic and histologic characteristics of the lesions in humans

INTRODUCTION

In animal models, active cooling of the electrode during radiofrequency (RF) ablation allows creation of larger lesions, presumably by increasing the power that can be delivered without coagulum formation. These RF lesions have not been characterized in human myocardium in regions of infarction and scarring.

METHODS AND RESULTS

Cooled-tip RF catheter ablation of ventricular tachycardias (VTs) was performed in two patients who had severe congestive heart failure and subsequently underwent cardiac transplantation. The first patient had four different monomorphic VTs. RF applications along the inferoseptal margin of a scarred region abolished all inducible VTs. The second patient had sarcoidosis involving the myocardium and four different inducible VTs. RF current applied at an inferobasal VT exit and at the right and left septa failed to abolish the VTs. The explanted hearts were examined at the time of cardiac transplantation 18 and 21 days later, respectively. Lesions extended to depths up to 7 mm, reaching clusters of myocardial cells deep to regions of fibrosis. Microscopically, the ablation sites contained coagulation necrosis with hemorrhage, surrounded by a rim of granulation tissue.

CONCLUSION

Saline-irrigated RF catheter ablation produces relatively large lesions capable of penetrating deep into scarred myocardium.

Proarrhythmia

Proarrhythmia is defined as the provocation of a new arrhythmia or the aggravation of a pre-existing one during therapy with a drug at doses or plasma concentrations below those considered to be toxic. Suggested criteria for proarrhythmia include (1) the new appearance of a sustained ventricular tachyarrhythmia; (2) change from a nonsustained to a sustained tachyarrhythmia; (3) acceleration of tachycardia rate; or (4) the new appearance of a clinically significant bradyarrhythmia or conduction defect. Proarrhythmia can be the direct result of a drug's electrophysiologic effects on conduction velocity, refractoriness, and automaticity. However, it may also be the result of metabolic abnormalities, changes in autonomic state, or drug/drug interactions that amplify or alter the drug's electrophysiologic effects. Some forms of ventricular proarrhythmia, such as torsade de pointes, are difficult to forecast and occur in patients with structurally normal hearts as well as in those with serious heart disease. Other forms of ventricular proarrhythmia, such as monomorphic ventricular tachycardia, occur predominantly in patients with structural heart disease or pre-existing ventricular arrhythmia. Atrial flutter with 1 : 1 conduction and bradyarrhythmias can be manifestations of proarrhythmia, particularly during drug therapy for atrial fibrillation. In patients with pacemakers or implantable cardiac defibrillators, antiarrhythmic drugs can change pacing thresholds and can alter the ability of a device to recognize or terminate a sustained ventricular tachyarrhythmia.

Entrainment mapping and radiofrequency catheter ablation of ventricular tachycardia in right ventricular dysplasia

OBJECTIVES

The purpose of this study was to determine if entrainment mapping techniques and predictors of successful ablation sites previously tested in coronary artery disease can be applied to ventricular tachycardia (VT) in arrhythmogenic right ventricular dysplasia (ARVD).

BACKGROUND

VT in ARVD has not been well characterized. Reentry circuits in areas of abnormal myocardium are the likely cause, but these circuits have not been well defined.

METHODS

Mapping of 19 VTs in 5 patients with ARVD was performed. At 58 sites pacing entrained VT and radiofrequency current (RF) was applied to assess acute termination of VT.

RESULTS

Sites classified as exits, central/proximal, inner loop, outer loop, remote bystander and adjacent bystander were identified by entrainment criteria. The reentrant circuit sites were clustered predominantly around the tricuspid annulus and in the right ventricular outflow tract (RVOT). RF ablation acutely terminated VT at 13 sites or 22% of the applications. Of the 19 VTs, eight were rendered noninducible and three were modified to a longer cycle length. In 2 patients ablation at a single site abolished two VTs.

CONCLUSION

VT in ARVD shows many of the characteristics of VT due to myocardial infarction. Entrainment mapping techniques can be used to characterize reentry circuits in ARVD. The use of entrainment mapping to guide ablation is feasible.

Recipient-to-donor atrioatrial conduction after orthotopic heart transplantation: surface electrocardiographic features and estimated prevalence

Recipient-to-donor atrioatrial conduction across a suture line has been rarely reported after orthotopic heart transplantation. The relation of such conduction to symptomatic arrhythmias and its prevalence are not known. Recipient-to-donor atrioatrial conduction was demonstrated in a 28-year-old woman with paroxysmal supraventricular tachycardia 7 years after orthotopic heart transplantation. Atrial tachycardia in the recipient atria conducted 2:1 to the donor atria and was eliminated by radiofrequency catheter ablation of a left-sided atrioatrial electrical connection. The electrocardiogram at rest and during exercise, recorded before ablation of the recipient-to-donor connection, showed frequent atrial premature complexes, with variable coupling to the preceding sinus beats, and a change in P-wave morphology during exercise, which reverted to normal during the recovery period. These findings were eliminated by ablation of the recipient-to-donor connection. To determine the prevalence of recipient-to-donor atrioatrial conduction late after transplantation, we evaluated the exercise electrocardiograms of 50 subjects > 5 years after heart transplantation for these features of recipient-to-donor conduction. At least 1 feature was present in 5 subjects, and both were present in 1 subject. Electrical conduction can occur across surgical suture lines in the atria. Recipient-to-donor atrioatrial conduction may occur in < or = 10% of patients late after heart transplantation. It is a potential cause of arrhythmias that can be effectively treated with radiofrequency catheter ablation.

Radiofrequency catheter ablation of ventricular tachycardia after myocardial infarction

BACKGROUND

Patients with ventricular tachycardia (VT) after myocardial infarction often have multiple morphologies of inducible VT, which complicates mapping and is viewed by some as a relative contraindication to ablation. Attempting to identify and target a single "clinical" VT is often limited by inability to obtain 12-lead ECGs of VTs that are terminated emergently or by defibrillators. This study assesses the feasibility of ablation in patients selected without regard to the presence of multiple VTs by targeting all VTs that allow mapping.

METHODS AND RESULTS

Radiofrequency catheter ablation targeting all inducible monomorphic VTs that allowed mapping was performed in 52 patients with prior myocardial infarction. Antiarrhythmic drug therapy had failed in 41 (79%) patients including amiodarone in 36 (69%) patients. An average of 3.6+/-2 morphologies of VT were induced per patient. More than 1 ablation session was required in 16 (31%) patients. Complications occurred in 5 (10%) patients, including 1 (2%) death caused by acute myocardial infarction. During follow-up 59% of patients continued to receive amiodarone; 23 (45%) had implantable defibrillators. During a mean follow-up of 18+/-15 months (range 0 to 51 months) 1 patient died suddenly, 2 died from uncontrollable VT, and 5 died from heart failure. Three-year survival rate was 70+/-10%, and rate for risk of VT recurrence was 33+/-7%.

CONCLUSIONS

Radiofrequency catheter ablation controls VT that is sufficiently stable to allow mapping in 67% of patients despite failure of antiarrhythmic drug therapy and multiple inducible VTs. However, ablation was largely adjunctive to amiodarone and defibrillators in this referral population.

Identification and ablation of macroreentrant ventricular tachycardia with the CARTO electroanatomical mapping system

Monomorphic ventricular tachycardias associated with regions of scar are most commonly due to reentry. Catheter based techniques have recently been described for mapping of reentry circuits. Fluoroscopic methods have obvious limitations when attempting to map large ventricular reentry circuit and localize target-sites of radiofrequency ablation. Three-dimensional right ventricular endocardial mapping was performed in a 38-year-old patient with ventricular tachycardia 28 years after surgical correction of tetralogy of Fallot by using the CARTO electroanatomical system. The map of electrogram voltage showed low amplitude electrograms over the anterior wall of the right ventricle extending into the right ventricular outflow tract, consistent with the location of the ventriculotomy scar. Recording of local activation time was combined with entrainment mapping to define the macroreentrant circuit during ventricular tachycardia. Since the activation propagated through a broad path around the right ventriculotomy scar, ablation was performed by creating a line of block, which was facilitated by tagging of the lesion sites on the endocardial activation map. Large ventricular reentry circuits can be identified and interrupted by creation of a line of block to interrupt a broad path. A practical approach to mapping combining analysis of electrogram voltage, activation sequence, and entrainment is presented.

Pace-mapping conduction delay at reentry circuit sites of ventricular tachycardia after myocardial infarction

This study was carried out to determine the relationship of conduction delay during pace-mapping, as indicated by the stimulus to QRS interval to different reentry circuit sites and bystanders, as identified by entrainment criteria, in patients with ventricular tachycardia late after myocardial infarction. Catheter mapping and ablation were performed in 40 patients with ventricular tachycardia after myocardial infarction. Data were retrospectively analyzed from 122 endocardial sites which met the following the criteria: a 12-lead electrocardiogram was recorded during pace-mapping, ventricular tachycardia was then induced and entrained by pacing to classify the type of the site relative to the reentry circuit exit. By entrainment criteria 77 sites were in the reentry circuit (28 exit sites, 49 other circuit sites) and 45 sites were bystanders not in the reentry circuit. The average stimulus conduction delay at central/proximal sites was 103 +/- 43 ms, which was significantly longer than at exit (57 +/- 31 ms), outer loop sites (57 +/- 32 ms), and bystander sites (57 +/- 37 ms); P < 0.05. Pace-mapping revealed evidence of greater conduction delay at sites proximal to the reentry circuit exit, consistent with slow conduction between these regions and the border of the infarct. Exit sites and outer loop sites were more likely to be located along the border of the infarct, with less conduction delay evident during pace-mapping.

Anatomic and electrophysiologic relation between the coronary sinus and mitral annulus: implications for ablation of left-sided accessory pathways

To determine whether precise left-sided accessory pathway localization is possible from the coronary sinus, electrocardiogram (ECG) characteristics from the coronary sinus pair demonstrating earliest activation via the accessory pathway were compared to simultaneous mitral annular ablation catheter ECGs at successful ablation sites in 48 patients. To define the coronary sinus-mitral annular relation, the coronary sinus to mitral annulus distance (D) was measured at sequential distances from the coronary sinus os in 10 cadaver hearts. Mitral annular ECGs demonstrated earliest activation via the accessory pathway more frequently than the earliest coronary sinus pair (p < 0.001), more frequent continuous electrical activity (p < 0.001), and more frequent accessory pathway potentials (p < 0.01). D was >10 mm at 20, 40, and 60 mm, respectively, from the coronary sinus os. Coronary sinus ECGs do not precisely localize left-sided accessory pathways, which may be due in part to an average anatomic separation of more than 10 mm between the coronary sinus and accessory pathways bridging the mitral annulus.

Ablation therapy for cardiac arrhythmias

Ablation has become an important and, in some cases, the first-line therapy for a number of tachyarrhythmias. The feasibility of treating arrhythmias with ablation was initially demonstrated with surgical ablation techniques. Recently, catheter ablation techniques have replaced the surgical approach in nearly all cases. Catheter ablation is highly effective for the Wolff-Parkinson-White syndrome, atrioventricular nodal reentry, and atrial ectopic tachycardia. It is effective for atrial flutter, although approximately one quarter of patients treated with catheter ablation continue to require therapy for concomitant atrial fibrillation. The surgical maze procedure has proved to be feasible for preventing atrial fibrillation. The risks and long-term efficacy of catheter ablation maze procedures for atrial fibrillation need to be defined. The efficacy of ablation for ventricular tachycardia varies with the type of tachycardia. Catheter ablation is very effective for the rare idiopathic ventricular tachycardias that occur in structurally normal hearts and for bundle-branch reentry ventricular tachycardia, which occurs most frequently in patients with dilated cardiomyopathy. When performed at an experienced center, surgical ablation is an excellent option for selected patients with ventricular tachycardia due to prior myocardial infarction who have a discrete aneurysm but otherwise well-preserved ventricular function. Catheter ablation shows promise for this arrhythmia, but it can be offered only to those patients who have relatively slow tachycardias that allow catheter mapping. Substantial advances in mapping and ablation technology will continue to occur, allowing nonpharmacologic control of cardiac arrhythmias to be achieved in an ever greater number of patients.

Ablation of ventricular tachycardia due to a postinfarct ventricular septal defect: identification and transection of a broad reentry loop

INTRODUCTION

Ventricular tachycardia (VT) after postinfarct ventricular septal defect (VSD) repair has not been well characterized.

METHODS AND RESULTS

A 55-year-old man developed refractory VT after inferior wall infarction and VSD repair. Entrainment demonstrated a broad reentry circuit path (outer loop) between the tricuspid annulus and VSD patch. A series of radiofrequency (RF) lesions transected this path, abolishing VT and producing conduction block between the inferior and superior aspects of the basal right ventricular septum.

CONCLUSION

Some VTs have broad reentry loops requiring ablation by a series of RF lesions across the path to create a line of block. This approach is analogous to that for atrial flutter.

Catheter ablation of ventricular tachycardia after myocardial infarction: relation of endocardial sinus rhythm late potentials to the reentry circuit

OBJECTIVES

We sought to determine whether endocardial late potentials during sinus rhythm are associated with reentry circuit sites during ventricular tachycardia (VT).

BACKGROUND

During sinus rhythm, slow conduction through an old infarct region may depolarize tissue after the end of the QRS complex. Such slow conduction regions can cause reentry.

METHODS

Endocardial catheter mapping and radiofrequency ablation were performed in 24 patients with VT late after myocardial infarction. We selected for analysis a total of 103 sites where the electrogram was recorded during sinus rhythm and, without moving the catheter, VT was initiated and radiofrequency current applied in an attempt to terminate VT.

RESULTS

Late potentials were present at 34 sites (33%). During pace mapping, the stimulus-QRS complex was longer at late potential sites, consistent with slow conduction, than at sites without late potentials (p < 0.0001). Late potentials were present at 15 (71%) of 21 sites classified as central or proximal in the reentry circuit based on entrainment, but also occurred frequently at bystander sites (13 [33%] of 39) and were often absent at the reentry circuit exit (3 [23%] of 13). Late potentials were present at 20 (54%) of 37 sites where ablation terminated VT, compared with 14 (21%) of 66 sites where ablation did not terminate VT (p = 0.004). Ablation decreased the amplitude of the late potentials present at sites where ablation terminated VT.

CONCLUSIONS

Although sites with sinus rhythm late potentials often participate in VT reentry circuits, many reentry circuit sites do not have late potentials. Late potentials can also arise from bystander regions. Late potentials may help identify abnormal regions in sinus rhythm but cannot replace mapping during induced VT to guide ablation.