[Diagnostic accuracy of a protocol in the evaluation of unexplained syncope]. / Rendimiento diagnóstico de un protocolo de estudio del síncope de causa no aparente.

INTRODUCTION AND OBJECTIVES: To assess the diagnostic capacity of a protocol to study syncope of unknown cause in which electrophysiological studies and tilting table tests are selectively used. PATIENTS AND METHODS: The study was performed in 137 consecutive patients (94 men and 43 women, with a mean age of 57.6+/-18.3 years) with syncope of unknown cause after the initial clinical evaluation, who were divided into two groups. Group A consisted of 77 patients meeting any of the following criteria: a) presence of structural heart disease; b) abnormal ECG; c) presence of significant non-symptomatic arrhythmia in the Holter recording, and d) presence of paroxysmal palpitations. These patients initially underwent an electrophysiological study. Group B consisted of 60 patients not meeting any of the above criteria, who were initially submitted to tilting table tests.Results. In group A, the electrophysiological study was positive in 43 patients (55%). In group B, the tilting test was positive in 41 patients (68%). Among patients in group A with a negative study, 20 (59%) were submitted to the tilting table test, with positive results in 7 cases (35%). Five patients from group B with a negative tilting test underwent the electrophysiological study, which was negative in all of them. Overall, a positive diagnosis was achieved in 91 of 137 patients (66%). CONCLUSIONS: In patients with syncope of a non-apparent cause in the initial assessment, selective use of electrophysiological studies or tilting table tests, guided by clinical criteria, allows for a positive diagnosis in over 60% of the cases. Our results suggest that the tilting table test should be performed in cases of group A with a negative electrophysiological study.

[The significance of the elevation of basal and exercise segments on Q-leads after acute myocardial infarct]. / Significado de la elevación basal y al esfuerzo del segmento ST en derivaciones con onda Q tras un infarto agudo de miocardio.

INTRODUCTION: ST segment elevation on Q-leads has been related to a greater infarct size and to the existence of ventricular aneurysm. On the other hand, ST elevation during exercise testing has been related to the presence of myocardial viability. OBJECTIVES: In the present study we investigated the relation between ST segment elevation on infarct-related electrocardiographic leads at rest and during exercise with: a) the extension and severity of the regional dysfunction; b) the presence of myocardial viability (response to dobutamine), and c) the residual stenosis in the culprit artery. MATERIAL AND METHODS: The study group was composed of 51 patients; cardiac cathetherism (8 +/- 3 days) and exercise testing (8 +/- 2 days) were performed during the pre-discharge period. In contrast ventriculography (centerline method) we determined the circumferential extension (rads) and the severity (SD/rad) of the regional dysfunction at rest and after dobutamine (10 micrograms/kg/min). The minimal luminal diameter (MLD) in the culprit artery was also measured. Results are expressed as median [Q1-Q3] and the differences among the groups were assessed by Mann-Whitney U. RESULTS: Patients with ST segment elevation in two or more leads at rest (n = 36) showed a greater (41 [30-51] rads vs 20 [14-41] rads; p = 0.007) and more severe regional dysfunction (1.9 [1.5-2.5] SD/rad vs 0.6 [0.5-2.4] SD/rad; p = 0.01), less response to dobutamine (% of reduction of the dysfunction extension after dobutamine) (17 [0-42]% vs 50 [24-100]%; p = 0.004) and smaller MLD (0.5 [0-0.9] mm vs 0.8 [0.6-1.1] mm; p = 0.03). Likewise, patients with exercise-induced ST segment elevation (n = 28) showed less response to dobutamine (15 [0-45]% vs 40 [21-57]%; p = 0.03) and smaller MLD (0.5 [0-0.7] mm vs 0.9 [0.5-1] mm; p = 0.02). There were non significant differences between patients with and without ST elevation during exercise in the extension or severity of the regional dysfunction. ST segment elevation both at rest (RR 0.2; CI 95% 0.04-0.85) and during exercise (RR 0.19; CI 95%: 0.05-0.69) decreased the probability of improvement with dobutamine. CONCLUSIONS: We conclude that ST segment elevation on Q-leads at rest is related to a more extended and severe dysfunction. Patients with ST segment elevation (at rest or during exercise) show less response to dobutamine (myocardial viability less likely) and a more severe residual coronary stenosis.