Post-myocardial infarction arrhythmia risk stratification using microvolt T-wave alternans.

Since its initial description, a number of studies have described the use of microvolt T-wave alternans (MTWA) as a predictor of the primary or secondary occurrence of ventricular arrhythmic events. These studies, however, have been limited by small sample sizes and disparate patient populations. Studies of MTWA in post-myocardial infarction (MI) patients are few in number, but hold predictive value for risk of ventricular arrhythmias. We performed a study of MTWA in post-myocardial infarction patients to clarify the predictive accuracy and usefulness of MTWA compared to other invasive and non-invasive techniques. We enrolled 120 patients (74 men, 46 women, mean age 62.3 ± 15.2 years in men, and 64.2 ± 13.8 years in women) with a history of myocardial infarction but no prior sustained ventricular arrhythmias. Patients were assessed by echocardiography, Holter, signal averaged ECG, MTWA, and electrophysiology study. Mean follow-up was 14 months. The MTWA test had a good negative predictive value for arrhythmic events in post-MI patients and can be used for risk stratification. We consider that in patients with positive MTWA further invasive evaluation, respectively electrophysiology study, is necessary.

A cause of falsely high noise level in signal averaged electrocardiogram recordings.

Signal averaged electrocardiogram (SAECG) is a well-established noninvasive method of exploration in patients at risk for sudden cardiac death. The time-domain SAECG analysis has a set of well-defined standards, including the value of accepted noise level. In very rare instances, the final noise level appears to remain unacceptably high even after carefully preparing the skin of the patient and averaging a great number of QRS complexes. We encountered three such cases in patients who had a SAECG done for a 40 Hz high-pass filter, which showed a high noise level in contrast with the visual impression of a good quality of the recording.

Invasive thymoma.

Thymomas are rare tumors of the thymic epithelium with a broad spectrum of morphological and clinical features. Despite a benign histological appearance, it can invade nearby structures or metastasize. The majority of patients are asymptomatic, but some may present with paraneoplastic syndromes such as myasthenia gravis, red cell aplasia, or hypogammaglobulinemia. Various staging systems of thymomas have been defined based on the degree of invasiveness. According to the WHO Classification, there are six histologic types of thymic epithelial tumors. The most important prognostic factor is the stage according to Masaoka's system. We report a case of invasive thymoma diagnosed incidentally in a patient with cardiovascular risk factors referred to the cardiologist with suspected thoracic aorta aneurism.

Pharmacokinetic based adjustment of lidocaine antiarrhythmic schedule.

Administration of lidocaine, 200 mg/day i.m. or 275 mg orally, decreased sudden death after myocardial infarct (from 20.7% to 10.3%) although such schedules are not considered adequate to guarantee efficient plasma levels. Inclusion of lidocaine in a polyethylene matrix assured a slow release and complete disappearance of known side effects. Lidocaine was administered 200 mg intramuscularly to hospitalized patients every 6 h or 275 mg oral tablets to healthy volunteers every 8 h and plasma levels evaluated. Plasma levels after oral administration to healthy volunteers showed a great variability, so that it was not possible to draw a statistically significant conclusion about the accumulation of lidocaine in a period of 1 week. In coronary artery disease patients, plasma levels slowly increased with time, but clinical signs indicated, in some cases, a much more rapid accumulation. The therapeutic efficiency at low repeated doses was explained as a consequence of a slow accumulation on the one hand and of the addition of the action of MEGX, the major metabolite of lidocaine, on the other hand.