Exercise testing and thallium-201 myocardial perfusion scintigraphy in the clinical evaluation of patients with Wolff Parkinson White syndrome.

In 58 patients with Wolff Parkinson White syndrome (WPW), we performed exercise stress testing in order to investigate the incidence of normalization of the auriculo-ventricular conduction and the ST-segment changes. For a more accurate evaluation of the latter, exercise and redistribution radionuclide images with Thallium-201 were obtained in 18 cases. Forty-nine had type A and nine had type B of WPW. Forty-eight had permanent, four had alternant and six had no pre-excitation (PE) when they started the test. Mean maximal functional capacity, mean maximal heart rate and mean maximal double product were not different when compared to an age-matched control group. Of the 48 patients who began the test with PE, in 23 (48%) it disappeared while PE persisted in 25 (52%). In 16 cases the disappearance of the PE was sudden and in seven it was progressive. Pre-excitation persisted in 39.5% of patients with type A and in 88.8% with type B (p less than 0.01). ST-segment depression was observed in 76.6% of patients with PE and in 28.6% of cases without PE (p less than 0.01). ST-segment depression occurred in 44.8% of patients with type A and in 100% of cases with type B (p less than 0.05). Transient abnormal Thallium-201 scans were observed in 62.5% of patients without PE and in 20% with PE. No patients showed exertional arrhythmias. This study suggests the possibility of measuring the duration of the refractory period of the accessory pathway in those patients in which the PE disappears suddenly, at a given heart rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Predictive value of changes in R-wave amplitude after exercise in coronary heart disease.

To assess the predictive value of coronary events reflected by changes in R-wave amplitude after exercise, 146 patients with angiographically documented coronary heart disease were studied. All patients were followed up for 6 years, during which time myocardial infarction and death of cardiovascular origin were considered endpoints. The incidence of events in patients in whom R-wave amplitude decreased (normal response) and in those in whom R-wave amplitude did not change or increase (abnormal response) were compared. The incidence of coronary events in patients with a normal response was 23% and in those with an abnormal response, 45.8% (p less than 0.01). Correlating the results with several noninvasive and angiographic variables, an abnormal R-wave response showed a significantly higher rate of events in the subsets of patients with prior myocardial infarction, absence of cardiomegaly, maximal functional capacity lower than 4 METs, maximal heart rate higher than 140 beats/min and abnormal left ventricular function. Thus, the changes in R-wave amplitude after exercise is a variable that should be taken into account when assessing the risk of future events in patients with coronary heart disease.

Infarto de miocardio y sindrome de Wolff-Parkinson-White. Utilidad de la prueba de ajmalina. / Myocardial infarction and Wolff-Parkinson-White syndrome.Usefulness of ajmaline test

Se presentan los resultados obtenidos con la prueba de ajmalina en dos pacientes con sindrome de WPW. En uno de ellos existia una imagen de falsa necrosis de pared anterolateral, ocasionada por una forma tipo C de dicho sindrome, mientras que en el otro coexistia un verdadero infarto agudo de miocardio, que aparentaba gran extension. En ambos enfermos la prueba de ajmalina permitio establecer el verdadero origem de los cambios electrocardiograficos