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Chronic Chagas' myocarditis can alter the myocardial substrate in a way that facilitates the emergence of fatal VT in a way similar to the long-term consequences of myocardial infarction. Post-myocardial infarction and Chagas' VT share many similarities: they are both macroreentrant circuits, entrainable, involving any wall segment from the endocardium to the epicardium. However, as compared to patients with post-MI VT, Chagasic patients tend to be younger and have a higher left ventricular ejection fraction. It is assumed, therefore, that their prognosis is closely related to VT treatment rather than the progression of the myocardial damage caused by the disease itself. Although sudden death is a rare event in patients in NYHA functional class I and II treated with amiodarone, VT recurrence rate is 30% a year. Drug therapy is ineffective for patients with advanced heart failure (100% recurrence rate/40% mortality in 1 year). Open-chest surgery is effective but requires very specialized centers and great expertise making its widespread use unrealistic. The results of combining RF endo/epicardial catheter ablation are still disappointing. Thus, research protocols on the search for new ablation technologies may greatly impact overall mortality in this subset of patients. This review will focus on the limitations of the current catheter-based ablation technology and suggest that an alternative approach is urgently needed. Experimental evidence of the efficacy of near infrared Lasers for catheter ablation will be reported along with investigations of the optical properties of the chagasic myocardium in the near infrared region to indicate that it might be not only feasible but also an appropriate choice to treat these patients.

This case report describes the electrophysiological findings of a 62-year-old patient with chronic Chagas' disease and two distinct morphologies of sustained ventricular tachycardia that involved a mitral isthmus. Multiple RF applications were necessary to obtain a bidirectional conduction block in the mitral isthmus that was related to the interruption of both tachycardias. After the procedure, the patient presented massive cerebral infarction that progressed to coma and death. Autopsy showed acute and old lesions at the mitral isthmus and recent mitral annulus thrombosis.

The implantable cardioverter defibrillator (ICD) is highly effective in the treatment of ventricular arrhythmias (VA) responsible for sudden cardiac death. However, the probability of occurrence of these arrhythmic events in presence of cardiomyopathy remains uncertain. The aim of this study was to compare the probability of nonoccurrence of life-threatening VA in ICD recipients with Chagas' versus non-Chagas' heart disease. Over a mean follow-up of 10.5 months, 53 ICD recipients (mean age = 50.1 years, 48 male) were evaluated. Eleven patients had Chagas' heart disease, 19 had idiopathic dilated cardiomyopathy and 23 had ischemic cardiomyopathy. Ventricular tachyarrhythmias with a cycle length < 315 ms were considered life-threatening. The cumulative probability of nonoccurrence of life-threatening VA was examined by Kaplan-Meyer method and the outcomes were submitted to the log rank test. At 2 years, the cumulative probability of life-threatening VA nonoccurrence was 0 in the Chagas' heart disease group versus 40% up to 55 months of follow-up in the non-Chagas' disease group (P = 0.0097). Among patients with cardiomyopathies of different etiologies, those with Chagas' heart disease had the lowest cumulative probability of nonoccurrence of life-threatening VA, confirming its unfavorable prognosis and the importance of preventive measures against sudden death in this disease.

We report a case of a 63-year-old women with Chagas' disease and recurrent, syncopal VT treated by RF catheter ablation in whom endocardial application of RF energy was guided by nonsurgical epicardial mapping. The procedure was undertaken in the electrophysiology laboratory under deep anesthesia. VT was interrupted after 2.4 seconds of application and rendered noninducible afterwards. Two weeks after the procedure, a distinct morphology VT was induced by programmed ventricular stimulation, and the patient was started on amiodarone, remaining asymptomatic 12 months after the procedure.

The heart is the most commonly affected organ in chronic Chagas' disease, and lymphocytic myocarditis is often observed. However, the pathogenesis of chronic Chagas' heart disease is controversial. The purpose of this study was to determine whether in vivo T. cruzi antigens could be detected in hearts from patients with chronic Chagas' disease and to investigate whether a correlation between these antigens and the intensity of myocardial inflammation exists. We studied 16 patients with chronic Chagas' heart disease. Ten patients had severely impaired left ventricular function and refractory heart failure, and six had episodes of sustained ventricular tachycardia without severe left ventricular dysfunction. Eight patients underwent magnetic resonance imaging with gadolinium enhancement to guide endomyocardial and surgical biopsies to sites with more intense inflammatory processes. Myocardial specimens were studied with immunohistochemical techniques by using rabbit anti-T. cruzi immune serum to detect the presence of T. cruzi antigen. All patients had evidence of some myocarditis in at least one myocardial fragment. T. cruzi antigen was detected in 11 (69%) patients. T. cruzi antigens were detected in 10 (71%) of 14 regions with histopathologic evidence of moderate or severe myocarditis. In contrast, T. cruzi antigens were detected in 3 of 18 regions with only mild or absent myocarditis. There was a statistically significant correlation between the presence of T. cruzi antigens and moderate or severe myocarditis (chi-square = 5.169, p = 0.023). The results of this in vivo study demonstrate that T. cruzi antigens are frequently detected in chronic Chagas' heart disease. In addition, there is an association between the intensity of the inflammatory process and the presence of T. cruzi antigens. The presence of the T. cruzi antigen and its correlation with the severity of myocardial inflammatory process provide strong supportive evidence for the role of T. cruzi even in the chronic forms of Chagas' heart disease.

Unlabelled: The aim of the study was to register the prevalence of late potentials (LP) in patients with chronic Chagas' heart disease (CCD) and the relationship with sustained ventricular tachycardia (SVT). 192 patients (96 males), mean age 42.9 years, with CCD were studied through a Signal Averaged ECG using time domain analysis. According to presence or absence of bundle branch block (BBB) and SVT, four groups of patients were created: Group I (n = 72): without SVT (VT-) and without BBB (BBB-): Group II (n = 27): with SVT (VT+) and BBB-; Group III (n = 63): VT- and with BBB (BBB+); and Group IV (N = 30): VT+ and BBB+. The LP was admitted, with 40 Hz filter, in the groups without BBB using standard criteria of the method. In the group with BBB, the root-mean-square amplitude of the last 40 ms (RMS) < = 14 microV was considered as an indicator of LP., Results: In groups I and II, LP was present in 21 (78%) of the patients with SVT and in 22 (31%) of the patients with SVT (p < 0.001), with Sensitivity (S) 78%; Specificity (SP) 70% and Accuracy (Ac) 72%. LP was present in 30 (48%) of the patients without and 20 (67%) of the patients with SVT, in groups III and IV. p = 0.066, with S = 66%; SP = 52%; and Ac = 57%. In the follow-up, there were 4 deaths unrelated to arrhythmic events, all of them did not have LP. Eight (29.6%) of the patients from group II and 4 (13%) from group IV presented recurrence of SVT and 91.6% of these patients had LP., Conclusions: LP occurred in 77.7% of patients with SVT and without BBB. In the groups with BBB, there was association of LP with SVT in 66.6% of the cases. The recurrence of SVT was patient in 21% of the cases from which 91.6% had LP.

Cardiac arrhythmias are common in chagasic patients. Electrophysiologic study is an invasive procedure for the investigation of sinus node function, atrioventricular node conduction and intraventricular (His-Purkinje) conduction and the mechanism of tachycardias. It is useful in elucidating syncope, dizziness and tachycardiac palpitations that remain unexplained by non-invasive diagnostic methods. It is fundamental in directing non-pharmacological therapy, especially in "sudden death" survivors. Chagasic patients may benefit from electrophysiologic study after a critical clinical evaluation.

Introduction: Syncope in patients with chronic Chagasic heart disease (CCHD) is a frequent but poorly studied problem., Methods and Results: Fifty-three patients with CCHD and recurrent syncope were followed for 2 to 127 months. They were classified into the following groups: G-I (n = 15) without inducible ventricular tachycardia (VT) and normal HV interval; G-II (n = 17) with only inducible VT; G-III (n = 11) with only an abnormal HV interval; and G-IV (n = 10) with both an inducible VT and an abnormal HV interval. Empiric pharmacologic therapy was given in G-I; pharmacologic therapy guided by electrophysiologic study in G-II; atrioventricular pacing in G-III; and empiric pharmacologic with atrioventricular pacing in G-IV. Age and sex were similar among groups; New York Heart Association Functional Class I symptoms were more prevalent (P = 0.0001) in G-I. The ejection fraction by echocardiography was higher in G-I (P = 0.0122). The density of premature ventricular complexes by Holter monitoring was similar among groups. The complexity of premature ventricular complexes by Holter was significantly higher in G-II (P = 0.0270); this variable, analyzed from the exercise electrocardiogram, was not different among groups. All deaths were sudden, prevalence was higher in G-II and absent in G-III, and recurrence of syncope was similar among groups., Conclusion: The most probable causes of recurrent syncope were VT (43%) with poor prognosis, and paroxysmal atrioventricular block (21%) with a favorable prognosis. Absence of congestive heart failure, complexity of premature ventricular complexes by Holter, and absence of intraventricular heart block showed statistical correlation with normal electrophysiologic study, inducible VT, and normal HV interval, respectively.

Purpose: To study the spontaneous variability of single (VPCs) and coupled (CVPCs) in patients with chronic Chagas' disease (CCD)., Patients and Methods: Twenty patients with CCD, 14 male, in class I and II NYHA, with frequent VPCs and VCPCs, free of drug therapy were studied. 21 hour Holter monitoring was done for 4 subsequent days. The data analysis assessed the variation in the frequency of VPCs and CVPCs between patients, seven hour periods one hour periods in a hierarchical model by a Poisson process., Results: a) the frequency of VPCs follows a circadian rhythm, closely related to the hourly variations of the mean heart rate; b) disregarding the heart rate influence on the variability of the ventricular arrhythmia, its behavior was at random and unpredictable; c) the minimal percentual reduction in VPCs/h that discriminated between antiarrhythmic effect and spontaneous between antiarrhythmic effect and spontaneous between antiarrhythmic effect and spontaneous variability was 121.86% for seven-hour, 58.42% for 21-hour and 38.45% for 42-hour electrocardiographic monitoring periods; d) the same approach for the VCPCs revealed values of 133.6%, 63.21% and 41.3% respectively., Conclusion: The large variability of ventricular arrhythmia in CCD during a 24 hour period makes necessary observations always longer. The minimal percentual reduction in VPCs/h that discriminated between antiarrhythmic effect and spontaneous variability might be 58.42% for two 21-hour electrocardiography monitoring periods.

Purpose: To evaluate the efficacy and safety of long-term empiric amiodarone therapy in patients with recurrent Sustained Ventricular Tachycardia (SVT) and Chronic Chagasic Myocarditis (CCM)., Patients and Methods: Thirty-five patients with CCM and SVT, eighteen (51%) of them were refractory to other antiarrhythmic drugs. The Amiodarone loading dose was between 600 and 1200 mg/day, mean of 883 +/- 239 mg/day, from a period of one to four weeks. The maintenance dose was decreasing in the follow-up period, it fell down to 356 +/- 125 mg/day at the end of six to 80 (mean = 27 +/- 20) months. Cumulative, event-free interval curves were generated by the Kaplan-Meier method. Clinical variables were compared with the use of the Student t-test or by means of chi-square tests., Results: The probability to suppress SVT was, 0.62 in 12 months, 0.56 in 24 months and 0.44 in 36 months, with regular use of amiodarone. The probability to the occurrence of sudden death was 0.0 in 12 months, 0.04 in 24 months and 0.11 in 36 months. The stratification of risk to clinical recurrence was significative to the left ventricular disfunction. All patients with functional class III or IV and LV ejection fraction less than 30% at radioisotopic ventriculography had clinical recurrence, while just 30% of patients with functional class I and II have got it (p less than 0.05). Fifteen (42.8%) patients had side effects. The treatment was discontinued in four patients (11.5%)., Conclusion: The empiric treatment with amiodarone apparently was effective in patients with SVT and CCM and functional class I and II. Patients with functional class III and IV did not get benefits from the treatment. In these cases other therapy must be pointed out.