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An aging general population, coupled with improved treatments for those individuals with coronary artery disease, hypertension, or heart failure, has led to a dramatic increase in the prevalence of atrial [...]

Arrhythmic events are responsible for the majority of sudden cardiac deaths after myocardial infarction. Many clinical studies have suggested that patency of the infarct-related artery, achieved by thrombolytic therapy or revascularization procedures, is a predictor of survival rates irrespective of myocardial salvage. The open-artery hypothesis suggests that an open infarct-related artery may result in other potential mechanisms, of benefits including electrical stability. This review focuses on the various levels and types of evidence supporting this contention. Copyright (C) 2000 by W.B. Saunders Company Progress in Cardiovascular Diseases, Vol. 42, No. 6 (May/June), 2000: pp 439-454

The purpose of this study was to evaluate the signal processing and analysis methods currently in use for the P wave signal-averaged electrocardiogram and to define optimal parameters for its use. P wave signal-averaged electrocardiograms using the QRS as a trigger for alignment of the analysis window were obtained in 15 subjects with prior atrial fibrillation and 15 controls. Five methods of signal filtering (unidirectional, bidirectional, finite impulse response, least squares fit, and spectral fast-Fourier transform) and three filter frequencies (14, 29, and 60 Hz) were compared with logistic regression analysis. Analysis techniques, including P wave vector duration, individual orthogonal lead duration, and terminal root mean square voltage were also evaluated for the strength of their association with the occurrence of atrial fibrillation. The least-squares fit filter with bandwidth filtering of 29 to 250 Hz produced the strongest association with atrial fibrillation (odds ratio 26). A high correlation (r > 0.92) was noted among the individual orthogonal leads; however, neither individual leads nor total atrial activation determined from individual leads demonstrated a superior association with atrial fibrillation when compared with total vector P wave duration. Terminal P wave RMS voltages were not significantly different between patients with prior AF and controls. (Am Heart J 1997;134:985-93.)

The P wave signal-averaged electrocardiogram is designed to predict the development of atrial fibrillation. This review will discuss the methodology and summarize the published experience with the P wave signal-averaged electrocardiogram.

Atrial fibrillation (AF) is the most common sustained arrhythmia occurring after cardiac surgery. Beside important implications regarding patient recovery, AF has been shown to substantially lengthen hospital stay-our recent study found a 3-day prolongation after adjusting for all other significant factors. Identification of those at highest risk of AF by clinical or noninvasive characteristics may be a useful strategy for targeted prophylactic therapy. Our data have shown that prolonged atrial conduction as assessed by analysis of the P wave duration from the signal-averaged electrocardiogram (SAECG) imparts a four fold increase in risk for postoperative AF, independently of other measured variables. In addition, abnormal conduction was present on the preoperative P wave ECG (P-SAECG), implying a preexisting substrate that is triggered by surgery. The use of combination abnormal noninvasive variables (eg, abnormal P-SAECG and low left ventricular ejection fraction) can identify groups with a 50% risk of AF, which is nine times as high as when both tests are normal. Thus, the P-SAECG is a useful and accurate predictor of AF after cardiac surgery.

Supraventricular tachyarrhythmias occur quite commonly and are now evaluated more often because of technological advances in the field of electrophysiology. Arrhythmias that involve the sinus node, namely, the syndrome of inappropriate sinus tachycardia and sinus node reentry, are rare. Because of their origin in the sinus node, the surface electrocardiogram (ECG) in these patients can present a diagnostic challenge to the clinician and in fact may elude recognition as an abnormal heart rhythm. Presented in this review are the clinical characteristics of these arrhythmias, as well as the mechanisms of action. Pharmacotherapy may be therapeutic in certain patients in preventing recurrences; however, radio-frequency catheter ablation offers a lifelong curative effect for these patients.

Objectives: The purpose of the study was to define the incidence of systemic embolism after cardioversion in patients with left ventricular (LV) thrombus. Background: The risk of systemic embolization after cardioversion in patients with an atrial thrombus is well known. However, data on thromboembolic events after cardioversion in patients with LV thrombus are limited because of hesitance to perform cardioversion in this population. Methods: Transthoracic and transesophageal echocardiograms acquired between January 1996 and October 2001 at our institution were reviewed for presence of LV thrombus in two orthogonal apical views. A total of 413 patients had echocardiographic evidence of LV thrombus. Medical records were reviewed for cardioversion performed within 3 weeks of the echocardiogram. Results: A total of 21 patients, age 66 +/- 10 years and ejection fraction 22 +/- 10% were identified. Cardioversion was indicated for atrial fibrillation in 8 (38%) and ventricular tachyarrhythmia in 13 (62%) patients, and was performed emergently in 5 (24%), electively in 8 (38%), and during electrophysiology study in 8 (38%) patients. The time interval between diagnostic echocardiographic study and cardioversion was 6 +/- 5 (range 1-18) days. All thrombi were located in the apical LV and were described as laminated (71%) and protruding (29%), and measured 0.7 +/- 0.4 x 1.6 +/- 0.8 cm. Before cardioversion, 17 (81%) patients were anticoagulated with warfarin or heparin. During clinical follow-up of up to 1 year (153 +/- 150 days) anticoagulation with warfarin was given to 15 (71%) patients. No patient had clinically apparent embolic event, including stroke, during hospitalization or during outpatient follow-up. Conclusions: Embolism after cardioversion in patients with echocardiographic evidence of LV thrombus was not observed. Cardioversion seems to be safe and further prospective studies are needed to address this.