Localizing the critical isthmus of postinfarct ventricular tachycardia: the value of pace-mapping during sinus rhythm.

BACKGROUND: Most postinfarct ventricular tachycardias (VTs) are sustained by a reentrant mechanism. The "protected isthmus" of the reentrant circuit is critical for the maintenance of VTs and the target for catheter ablation. Various techniques based on conventional electrophysiology and/or detailed three-dimensional (3D) reconstruction of the VT circuit are used to unmask this isthmus. OBJECTIVE: The purpose of this study was to assess pace-maps (PMs) to identify postinfarct VT isthmuses. We hypothesized that an abrupt change in paced QRS morphology may be used to identify a VT isthmus and be targeted for successful ablation. METHODS: High-density 3D PMs were matched to the subsequent 3D endocardial reentrant VT activation mapping in 10 patients (8 men; age 70.7 ± 10.8 years) who underwent successful postinfarct VT ablation. At each pacing site in a given patient, the 12-lead ECG recorded during pacing was compared to that of VT, with the resulting matching percentage (up to 100% for perfect matches) allocated to this point to generate color-coded PMs. RESULTS: With respect to VT isthmuses, the best percentages of matching were found in the exit zones and isthmus exit part (89% ± 8% and 84% ± 7%, respectively) and the poorest adjacent to scar border in the outer entrance zones (23% ± 28%), in the entrance zones (39% ± 34%), and in the entrance part of the isthmus (32% ± 26%). The color-coded sequence (from the best to the poorest matching sites) on the PMs revealed figure-of-eight pictures matching the VT activation time maps and identifying VT isthmuses. CONCLUSION: Pace-mapping is useful for unmasking VT isthmuses in patients with well-tolerated postinfarct endocardial reentrant VTs.

Showing up channels for postinfarct ventricular tachycardia ablation.

The number of scar-related ventricular tachycardia (VT) ablation procedures is increasing worldwide. This is certainly due to the ever growing number of patients implanted with an implantable cardioverter defibrillator in whom an ablation procedure may be required to better control the ventricular arrhythmia burden, but is also likely related to our better understanding of the arrhythmias mechanisms as well as the improvement of the mapping techniques during the last 15 years. Most VTs, especially those arising after myocardial infarction, depend on a critical isthmus. Defining precisely the critical isthmus of postinfarct VT may be challenging, particularly when the arrhythmia is poorly tolerated. In the literature, there are extensive data concerning the value of conventional electrophysiological techniques, especially entrainment mapping in association with postpacing interval measurements, regarding the identification of postinfarct VT isthmuses. There are, however, other--sometimes emerging--approaches to image critical postinfarct VT channels. We have summarized these, reviewing data from the published literature as well as our own experience.

Safety and efficacy of programming a high number of antitachycardia pacing attempts for fast ventricular tachycardia: a prospective study.

AIMS: Little is known about the optimal number of antitachycardia pacing (ATP) attempts to programme in the fast ventricular tachycardia (FVT) zone. We sought to analyse the long-term efficacy and safety of programming a high number of ATP attempts for FVTs. METHODS AND RESULTS: All patients receiving an implantable cardioverter/defibrillator (ICD) for coronary artery disease or dilated cardiomyopathy for primary and secondary prevention between 2000 and 2009 were prospectively included. Implantable cardioverter/defibrillators were programmed to deliver 10 ATP attempts for FVT cycle lengths (CLs) of 250-300 ms (200-240 b.p.m.) before shock delivery (5 bursts, then 5 ramps; 8-10 extrastimuli at 81-88% FVT CL; minimal pacing CL 180 ms). Among 770 patients included and followed for 40.6 ± 25.6 months, 137 (17.8%) experienced a total of 1839 FVTs, 1713 of which were ATP-terminated (unadjusted efficacy = 93.1%, adjusted = 81.7%), 106 ATP-accelerated (5.8%), and 20 ATP-resistant (1.1%). The majority of FVT episodes were successfully treated by one or two attempts (98.3%). However, patient-based analysis showed that 17 (12.4%), 8 (5.8%), and 5 patients (2.1%) had at least one episode treated by three or more, four or more, and five or more ATP attempts. The benefit of this strategy was reduced after five attempts. The majority of FVT episodes was asymptomatic and diagnosed at device interrogation during follow-up: syncope and pre-syncope occurred in only 0.2 and 0.4% of episodes, respectively. CONCLUSION: Programming a high number of ATP attempts (up to five ATP attempts) in the FVT zone is both safe and efficient and could prevent shocks in numerous ICD recipients.

Incidental extracardiac findings in cardiac computed tomography performed before radiofrequency ablation of atrial fibrillation.

BACKGROUND: Radiofrequency ablation has became a validated therapeutic technique for symptomatic drug refractory atrial fibrillation (AF). Cardiac computed tomography (CT) is used to evaluate left atrial (LA) anatomy in order to improve AF ablation. The analysis of noncardiac structures during cardiac CT may identify clinically significant incidental findings (IFs). The objective of this study was to determine the prevalence of IF in patients undergoing AF catheter ablation. METHODS: Between February 2008 and March 2010, all patients planned for a first procedure of AF or LA tachycardia (LAT) ablation underwent a cardiac CT scan and were retrospectively included in this study. Extracardiac IFs were considered to be present if an abnormality was identified without previous clinical suspicion or known disease. RESULTS: Two hundred and fifty patients (55.2 ± 9.6 years of age, 82.4% men) were enrolled (133 paroxysmal, 43 persistent, 58 permanent AF, and 16 LAT). Fifty-eight patients (23.2%) had a total of 76 IFs. Patients with IF were significantly older (59.5 ± 8.2 vs 53.8 ± 9.7 years old, P < 0.001). No relationship existed between the type of arrhythmia and IF existence. The majority of IFs were pulmonary (50%), with 15.8% of pulmonary emphysema. Two cases of lung cancer and of pulmonary fibrosis, 15 mediastinal adenopathies, and three congenital coronary arteries anomalies were found. CONCLUSIONS: Cardiac CT scan is a useful tool to evaluate LA morphology before AF ablation. However, as a considerable prevalence of IF was found in our study, extracardiac structures should be routinely analyzed to detect unknown conditions, which could require specific management.

Myocardial infarction in a 45-year-old man following an anaphylactic reaction to a wasp sting.

We present the case of a 45-year-old man with clinical features of acute coronary syndrome with persistent ST segment elevation following an anaphylactic reaction to a wasp sting treated with adrenaline. A thrombolysis is performed with no effect on clinical signs, leading to an emergency cardiac catheterization which reveals a non-occlusive thrombosis of the right coronary artery. The pathophysiology and clinical implications of this association are discussed.

Factors likely to affect the long-term results of ventricular stimulation after myocardial infarction.

BACKGROUND: The results of programmed ventricular stimulation (PVS) may change after myocardial infarction (MI). The objective was to study the factors that could predict the results of a second PVS. METHODS: Left ventricular ejection fraction (LVEF) and QRS duration were determined and PVS performed within 3 to 14 years of one another (mean 7.5+/-5) in 50 patients studied systematically between 1 and 3 months after acute MI. RESULTS: QRS duration increased from 120+/-23 ms to 132+/-29 (p 0.04). LVEF did not decrease significantly (36+/-12 % vs 37+/-13 %). Ventricular tachycardia with cycle length (CL) > 220ms (VT) was induced in 11 patients at PVS 1, who had inducible VT with a CL > 220 ms (8) or < 220 ms (ventricular flutter, VFl) (3) at PVS 2. VFl or fibrillation (VF) was induced in 14 patients at PVS 1 and remained inducible in 5; 5 patients had inducible VT and 4 had a negative 2nd PVS. 2. 25 patients had initially negative PVS; 7 had secondarily inducible VT, 4 a VFl/VF, 14 a negative PVS. Changes of PVS were related to initially increasing QRS duration and secondarily changes in LVEF and revascularization but not to the number of extrastimuli required to induce VFl. CONCLUSIONS: In patients without induced VT at first study, changes of PVS are possible during the life. Patients with initially long QRS duration and those who developed decreased LVEF are more at risk to have inducible monomorphic VT at 2nd study, than other patients.

Complete atrioventricular block during ablation of atrial flutter.

We report the case of a 51-year-old patient who developed a complete atrioventricular (AV) block during the isthmic radiofrequency catheter ablation of a typical atrial flutter. The cause was an acute occlusion of the segment three of the right coronary artery. His recanalization was associated with the immediate restoration of a normal AV conduction. The complication is exceptional (one of 740 consecutive atrial flutter ablations). (PACE 2010; 516-519).

Rapid and low-cost method to prove the nature of no documented tachycardia in children and teenagers without pre-excitation syndrome.

Aims Symptoms in children are often difficult to interpret. The purpose of this study was to report the results of transoesophageal electrophysiological study (EPS) performed in children complaining of sudden onset tachycardia with normal non-invasive studies. Methods and results Eighty-two children and teenagers (mean age 15 +/- 3 years) presented with suspected but no documented paroxysmal supraventricular tachycardia (SVT). ECG was normal. Non-invasive studies were negative; 23 children had syncope with tachycardias. They underwent transoesophageal EPS in our out-patient clinic. The mean duration of transoesophageal EPS was 11 +/- 5 min. Electrophysiological study was negative in 25 children. AV nodal re-entrant tachycardia could be induced in 37 children, 11 of them associated with syncope. Wolff-Parkinson-White syndrome (WPW) was diagnosed in five children in which atrioventricular re-entrant tachycardia was inducible. Atrioventricular re-entrant tachycardia due to a concealed AP was induced in 14 children. Verapamil-sensitive ventricular tachycardia was induced in one patient. Factors associated with tachycardia inducibility were an older age (15.5 +/- 2 vs. 14 +/- 4 years) (P < 0.05) and the absence of syncope (81 vs. 52%) (P < 0.05). During a mean follow-up of 3 +/- 1 year, no patient with negative EPS developed documented tachycardia. In 17 children with inducible SVT, radiofrequency ablation of the re-entrant circuit was subsequently performed. Conclusion Transoesophageal EPS is a fast method for proving the nature of paroxysmal tachycardia in children and teenagers presenting with normal ECG and for demonstrating WPW syndrome not visible on standard ECG. The negative predictive value of transoesophageal EPS for the diagnosis of SVT was 100%.

Nonischemic dilated cardiomyopathy: results of noninvasive and invasive evaluation in 310 patients and clinical significance of bundle branch block.

BACKGROUND: The survival of patients with idiopathic dilated cardiomyopathy (IDCM) at III and IV stages of New York Heart Association (NYHA) is decreased in those with a bundle branch block (BBB) compared to those without BBB. Less is known on the prognosis of patients at earlier stages of NYHA and who had a left BBB (LBBB) or right BBB (RBBB). We sought to evaluate the prevalence and the clinical significance of LBBB or RBBB in patients with IDCM and classes I and II of NYHA. METHODS: Clinical data, noninvasive, and invasive studies were consecutively collected in 310 patients, with IDCM, followed up to 4.8+/-3.7 years. RESULTS: Seventy-six patients (25%) had LBBB, 21 (7%) had RBBB, and 212 had no BBB. Patients with BBB were older than other patients (P < 0.009). Left ventricular ejection fraction (LVEF) was lower in LBBB than in RBBB and other patients (P < 0.05). Syncope was more frequent in BBB than in absence (P < 0.05). Incidence of spontaneous ventricular tachycardia (VT) and atrial fibrillation, VT induction, total cardiac events, and sudden death were similar in the presence or absence of BBB. Deaths by heart failure and heart transplantations tended to be more frequent in BBB than in absence. CONCLUSIONS: LBBB was present in 25% of patients with IDCM; RBBB was rare. Patients with BBB were older and had more frequent syncope than patients without BBB; LVEF was lower in LBBB than in RBBB or in absence of BBB. BBB did not increase the risk of spontaneous VT, VT induction, or sudden death, and tended to increase deaths by heart failure and the indications of heart transplantation.

Are the results of electrophysiological study different in patients with a pre-excitation syndrome, with and without syncope?

AIMS: Syncope in Wolff-Parkinson-White (WPW) syndrome may reveal an arrhythmic event or is not WPW syndrome related. The aim of the study is to evaluate the results of electrophysiological study in WPW syndrome according to the presence or not of syncope and the possible causes of syncope. METHODS AND RESULTS: Among 518 consecutive patients with diagnosis of WPW syndrome, 71 patients, mean age 34.5 +/- 17, presented syncope. Transoesophageal electrophysiological study in control state and after isoproterenol infusion was performed in the out-patient clinic. Atrioventricular re-entrant tachycardia (AVRT) was more frequently induced than in asymptomatic patients (n = 38, 53.5%, P < 0.01), less frequently than in those with tachycardia; atrial fibrillation (AF) and/or antidromic tachycardia (ATD) was induced in 28 patients (39%) more frequently (P < 0.05) than in asymptomatic patients or those with tachycardia. The incidence of high-risk form [rapid conduction over accessory pathway (AP) and AF or ATD induction] was higher in syncope group (n = 18, 25%, P < 0.001) than in asymptomatic subjects (8%) or those with tachycardias (7.5%). Maximal rate conducted over AP was similar in patients with and without syncope, and higher in patients with spontaneous AF, but without syncope. Results were not age-related. CONCLUSION: Tachycardia inducibility was higher in patients with syncope than in the asymptomatic group. The incidence of malignant WPW syndrome was higher in patients with syncope than in asymptomatic or symptomatic population, but the maximal rate conducted over AP was not higher and another mechanism could be also implicated in the mechanism of syncope.