BACKGROUND: In a prospective epidemiological study of chronic Chagas' disease, several clinical and echocardiographic variables were analyzed as predictors of mortality. METHODS: Among 960 subjects seropositive for Chagas' disease who were examined between June 1981 and June 1992, 283 had echocardiograms. RESULTS: During a mean follow-up period of 48.3 +/- 36.4 months (range, 1-156 months), 108 subjects died. Echocardiographic end-diastolic and -systolic left ventricular internal dimensions, fractional shortening, radius-to-thickness ratio, left ventricular mass, mitral E-point septal separation, and 17 other nonechocardiographic variables were predictors of death on univariate analysis (P < 0.001 for each). On stepwise multiple regression analysis of 215 subjects, significant risk covariates in a Cox model analysis were clinical group (P < 0.0001), M-mode echocardiographic E-point septal separation of 22 mm (P = 0.003), presence of first- or second-degree heart block (P = 0.003), chest radiologic cardiothoracic ratio >/= 0.55 (P = 0.012), presence of electrocardiographic ST segment elevation on precordial leads (P = 0.014), age >/= 56 years (P = 0.028), and presence of right bundle-branch block (P = 0.045). Patients with an apical aneurysm on two-dimensional echocardiography had an increased mortality (Chi-square = 11.5, P < 0.001). CONCLUSIONS: Echocardiography is a valuable tool to assess the risk of death in prospective studies on chronic Chagas' heart disease.

Witnessed sudden cardiac death due to paroxysmal atrioventricular (AV) block during ambulatory monitoring occurred in a 56‐year‐old female with primary conduction system disease. The control tracings showed right bundle branch block. Holter recordings obtained during the fatal event revealed paroxysmal complete AV block followed by ventricular asystole of approximately 13 seconds which, in turn, preceded the emergence of a slow idioventricular rhythm. The patient was definitely alive 5 minutes and 10 seconds following the onset of the AV block (since she activated the event marker in the recorder twice) and, possibly, 8 minutes later. Complete AV block persisted until the cessation of all cardiac activity, which took place 47 minutes following the occurrence of AV block. It is very likely that this patient could have been resuscitated in a city having a rapidly responding rescue squad.

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Multiprogrammable dual-demand AV sequential (DVI, MN) pacemakers were implanted in twenty-three patients (in one of them a DVI, MN unit was used as a VVI, MN with the aid of an atrial plug) with supraventricular tachycardias after electrophysiological studies revealed a great variety of AV reentry circuits. The latter included tachycardias involving accessory pathways of the Kent type, manifest or concealed Wolff-Parkinson-White syndromes, nodo-ventricular (Mahaim) tracts, "enhanced" AV node (or extra AV nodal) pathways and dual AV pathways. In addition, multiprogrammable "non-committed" AV sequential (DVI, MN and DDD, M) pacemakers were permanently implanted to treat different forms of ventricular tachyarrhythmias that included: torsade de pointes in the Romano-Ward syndrome and Chagas' cardiomyopathy, ventricular tachycardia which is bradycardia-dependent (in Chagas' cardiomyopathy) and reciprocal beats induced by, and producing severe hemodynamic derangements in a patient with a conventional VVI unit. With small-size multiprogrammable units, arrhythmias may be treated by changing parameters non-invasively. By temporary inhibition, one may analyze the underlying rhythm and pacemaker dependency. In patients without chronic atrial flutter/fibrillation who require pacing and possibly tachyarrhythmia control, our experience with multiprogrammable "non-committed" AV sequential pacing has been very satisfactory. The evolution toward newer pacing modes which provide atrial sensing and tracking (DDD), and thus preserve AV synchrony over a wider range of atrial rates, may contribute even further to successful patient management. This may be applicable to pediatric patients as well.