Darío Di Toro

Fragmented Surface ECG Was a Poor Predictor of Appropriate Therapies in Patients with Chagas’ Cardiomyopathy and ICD Implantation (Fragmented ECG in CHAgas’ Cardiomyopathy Study)

Main causes of death in chronic Chagas’ cardiomyopathy (CChC) are progressive congestive heart failure and sudden cardiac death. Implantable cardioverter defibrillators (ICD) have been proved an effective therapy to prevent sudden death in patients with CChC. Identification of predictors of sudden death remains a challenge.

Predictors of All-Cause 1-Year Mortality in Implantable Cardioverter Defibrillator Patients with Chronic Chagas’ Cardiomyopathy

Background: Implantable cardioverter defibrillators (ICDs) have been used in the treatment of either sustained ventricular tachycardia or ventricular fibrillation in patients with Chagas’ cardiomyopathy. This study aimed at determining mortality rate and risk factors of all‐cause 1‐year mortality in primary and secondary ICD patients with Chagas’ cardiomyopathy.

Supraventricular tachycardia coexisting with apparent Mobitz I and II atrioventricular block: a single mechanism?

A 28-year-old man with a history of palpita-tionswasreferredforevaluation.Initialevaluationshowed a normal resting electrocardiogram withsinus rhythm and absence of structural heart dis-ease.AmbulatoryHoltermonitoringdemonstratedseveral episodes of self-terminated narrow QRScomplex tachycardia, as well as episodes of atri-oventricular (AV) block (Fig. 1).

Acompanhamento a longo prazo de pacientes com indicação de desfibrilador implantável como prevenção primária de morte súbita

BACKGROUND Recent MADIT II and SCD-HeFT trials have led to an expansion of indications for use of prophylactic Implantable Cardioverter Defibrillator (ICD) in patients with severe left-ventricular impairment. This therapy has not been fully adopted in our health care system, mainly due to its high cost. OBJECTIVE To assess total mortality of SCD-HeFT-like patients from our daily practice who are under stable, optimal medical treatment and who have not received an ICD; and to compare it to that of the placebo arm of the SCD-HeFT Trial. METHODS SCD-HeFT-like patients identified from office medical records were included in our study. Total mortality was assessed by telephone contact. Statistical analysis was performed by Students t-Test, Mann-Whitney Test or chi2 test, depending on the type of variable. Cumulative mortality rates were calculated according to the Kaplan-Meier method. RESULTS Our study comprised 102 patients (seventy-four of which were men) with a median age of 64 years, and an overall median ejection fraction of 25%. We found no differences between our patients and SCD-HeFT patients across these 3 variables. Over a 19.6-month follow-up period, 21 patients died (20.6%) vs. 28.8% of the SCD-HeFT patients. This difference was not statistically significant (p = 0.08). CONCLUSION SCD-HeFT-like patients from our practice had no difference in mortality rate than patients enrolled in the placebo arm of the SCD-HeFT trial. These results suggest that the SCD-HeFT population is representative of our patients.

Premature ventricular complexes ablation: A trip to the accuracy

Classically, premature ventricular contractions (PVC) have been considered relatively benign in the absence of structural heart disease. However, frequent PVC may result in left ventricular systolic dysfunction, a form of PVC-induced cardiomyopathy or PVC-mediated deterioration of pre-existing cardiomyopathy [1]. Frequent PVCs have been associated with a more than 2-fold higher risk of cardiovascular outcomes including stroke and mortality in some reports [2, 3]. Radiofrequency ablation (RFA) is increasingly being used in the treatments of symptomatic or frequent PCV. Some authors have reported that catheter ablation appears to be more effective than antiarrhythmic drugs in PVC frequency reduction and left ventricular ejection fraction normalization [4]. Electroanatomic mapping systems can be helpful, especially when multiple chambers need to be mapped and compared. Activation mapping is ideal for focal PVC and is done with point-by-point mapping if PVC frequency is adequate. Alternatively, with a multielectrode catheter, multiple points can be acquired in a single beat when the PVC is very infrequent (non-contact EnSite ArrayTM, St. Jude Medical, St. Paul, Minnesota, USA). In the current issue of “Cardiology Journal”, Dubner et al. [5] examined the utility of radiofrequency catheter ablation with a non-contact mapping system EnSite ArrayTM in patients with frequent PVC. The investigators included 18 patients with frequent PVC (> 6,000/24 h) who underwent PCV ablation mostly as a second line procedure. Eighty-eight point eight percent of the patients had no structural heart disease and 38% of them presented with ventricular tachycardia (VT) (25% non sustained VT and 13% monomorphic VT). The authors reported an acute success rate of 93.7% with a low complication rate. Li Zhong et al. [4] compare the relative efficacy of RFA and antiarrhythmic drugs (AADs) on PVC burden reduction increasing left ventricular systolic function. Five hundred and ten patients with frequent PVC (> 1,000/24 h) were treated either by RFA or with AADs. The authors report that an acute RFA success rate was 94%, defined as the elimination of PVCs at the end of the procedure [4]. The rate of acute success rate was very similar to reported by Dubner et al. [5]. It should be noted that in Li Zhong et al. [4] series, the RFA was done using a 3-dimensional electroanatomic mapping (Carto System, Biosense Webster, Inc., Diamond Bar, California, USA) without any non-contact mapping. Perhaps it would have been helpful to include a control group (without no contact mapping system) to compare if the non-contact mapping improves the efficacy and safety of the procedure in Dubner’s series. Because RFA of PCV is time consuming, it would be also interesting to know if the noncontact mapping system group procedure duration is shorter, because this would turn into a valuable tool to the electrophysiologist. A limitation of ARRAy system is the fact that its accuracy decreases significantly if the location of the PCV is away from the right ventricular outflow tract (RVOT), so it is essential to be certain about the PVC location before starting this procedure. The surface electrocardiogram (ECG) is a simple tool that can provide clues with respect to the

Multiple morphologies of ventricular tachycardia assessed by implantable cardioverter-defibrillator electrograms in a patient with Chagas disease, successfully treated with catheter ablation: modern problems, old solutions

A 60-year-old man with Chagas disease, implanted with an implantable cardioverter defibrillator (ICD), experienced electrical storm. The ICD-stored electrograms revealed several ventricular tachycardia (VT) episodes with two different morphologies, confirmed thereafter by surface electrocardiogram. Both VTs originated from two different re-entry circuits and were successfully ablated. This case highlights the usefulness of ICD electrograms in identifying two VTs as having different sites of origin. Analysis of implantable cardioverter-defibrillator electrograms (ICD-EG) showed that monomorphic ventricular tachycardia (VT) with different QRS morphologies during different episodes (multiple morphologies, MM) predicted higher mortality. 1 A 60-year-old man implanted with an ICD (Medtronic Maximo-VR7232) for secondary prevention of death, with Chagas disease and left ventricular ejection fraction (LVEF), 0.45 was hospitalized for electrical storm. The ICD interrogation revealed 62 episodes of monomorphic VT. Analysing ICD-EG, a difference in morphology was seen only in the HVA/HVB electrogram (a QS complex in Figure 1A; a Qr complex in Figure 1B). During hospitalization he experienced several VT episodes and surface-electrocardiogram Figure 1 Schematic representation of the endocardial surface of the left ventricle. (A) and (B) Implantable cardioverter defibrillator- stored electrograms showing two different morphologies of the HVA/HVB electrogram. Note that this difference is not evident in the Vtip-Vring electrogram

Diagnóstico diferencial entre doble respuesta ventricular y extrasistolia hisiana bigeminada

We have read with attention the scientific letter published by Evertz et al. entitled ‘‘Dual Ventricular Response: Another Road to Supraventricular Tachycardia in Dual Atrioventricular Nodal Physiology’’. As the authors clearly explain, their case concerned a form of supraventricular ‘‘pseudotachycardia’’ in which they established a differential diagnosis involving 2 conditions: atrial tachycardia (quickly ruled out during the electrophysiological study) and bigeminy arising from the bundle of His. The latter diagnosis is not easily differentiated. The authors ruled out premature contractions of the bundle of His due to the consistent relationship of the His and ventricular action potentials to the preceding atrial action potential. However, in the description of the electrocardiographic recording shown in Figure 1 of their letter, the authors mention certain irregularity of up to 50 ms in the PR2 interval. As they state in the text, the diagnosis of dual nodal physiology was more evident once the dual ventricular response had disappeared following ablation of the slow pathway. Our group reported a case of frequent extrasystoles arising from the bundle of His in which, as in that described by Evertz et al., the patient had been referred to us with palpitations and supraventricular tachycardia. Our patient showed a wider variability in the H1-H2 interval, which contributed to the presence of a greater number of beats with aberrant conduction and facilitated the differential diagnosis. Moreover, in our case, the presence of blocked P waves and ‘‘pseudoblock’’ of atrioventricular conduction was incompatible with the existence of dual nodal physiology. By way of this letter, we wish to stress how difficult it is on occasion to differentiate between these two conditions during the diagnostic stage of the electrophysiological study performed prior to ablation. The diagnosis of premature beats arising from the bundle of His can be confirmed using a detailed map of the region

Should we test all defibrillators at the time of implantation? An unanswered question.

We read with great interest the study of Vischer et al. entitled “Role of defibrillation threshold testing in the contemporary defibrillator patient population.”1 This is an interesting paper on a timely and relevant topic that retrospectively reviews data on 436 patients undergoing implantable cardioverter defibrillator (ICD) insertion with defibrillation threshold testing (DFT) in all cases (309 de novo implantations and 127 generator replacements). The authors conclude that shock testing should be performed in all patients, based on the finding that 9 (2%) patients could not be defibrillated with their standard approach, which was a 10 J safety margin. However, external rescue shock was necessary in only 5 (1.1%) patients, assuming that in the remaining 4 patients ventricular fibrillation spontaneously terminated or was defibrillated by a maximal output ICD shock. This issue is not completely clear in the paper, and more information on those 4 patients may contribute to a better understanding of DFT outcomes. Moreover, owing the lack of a nontested control group and follow-up, the recommendation to routinely perform DFT in all ICD implantations appears to be overstated, according to the findings of the study. In terms of patients’ characteristics, amiodarone therapy, dilated cardiomyopathy, and low ejection fraction were associated with shock testing failure in univariate analysis. However, a multivariate analysis (not shown) will be helpful to more accurately identify those patients at risk of an unsuccessful DFT.

Value of the electrocardiographic signs in differential diagnosis of atrioventricular nodal reentrant tachycardia

We read with great interest the article: ‘Value of the aVR lead in differential diagnosis of atrioventricular nodal reentrant tachycardia’ by Haghjoo et al. 1 in a recent issue of the journal. We would like to comment that the specificity of an electrocardiographic sign guarantees that in the presence of this sign, the likelihood of the disease in question is high. On the contrary, the sensitivity of a particular sign guarantees that in the absence of this sign, …

Termination mode of a broad QRS complex tachycardia: is the surface electrocardiogram the key?

A 45-year-old man with a long history of palpitations and absence of pre-excitation in baseline electrocardiogram underwent a Holter recording, revealing several episodes of regular non-sustained broad QRS complex tachycardia that terminated following the occurrence of a narrow QRS. (Panel A). The analysis of the last narrow QRS showed a signal compatible with a retrograde P wave. An electrophysiological study was performed. During the procedure, short episodes of orthodromic tachycardia (OT) with functional left bundle branch block (LBBB) were reproduced and consistently interrupted following the occurrence of a single narrow QRS complex with exactly the same cycle length as that of the tachycardia (Panel B). The intracardiac recordings showed a 40 ms shortening of the ventriculo-atrial interval in the narrow beat and an-