[Syncopes of unclear etiology. Diagnosis, follow-up observation and pacemaker therapy]

Clinical findings after syncopal attacks were evaluated in 295 inpatients for examining their clinical significance and the course and prognosis in syncopes of unclear aetiology. This was done after having defined the criteria for "very probable" and "possible" causes of the syncopes. A "typically rhythmogenic" anamnesis had a sensitivity rating of 79%. Long-term ECG proved the most frequent contribution to clarification. Doppler examination of the carotid artery was hardly relevant. Patients with tachycardia usually suffered from cardiac disease (coronary heart disease or cardiomyopathy). Bradycardia predominated in patients with a clinically "healthy" heart, especially in elderly patients. An overall percentage of 37% of the cases could not be clarified despite thorough clinical examination using all available diagnostic tools. Follow-ups over two years and outpatient examinations revealed a favourable prognosis in patients whose syncopes had remained unexplained: No further syncopes had occurred in 75% of these patients over a period of two years. In 12% of the subjects the cause was identified by the follow-up examinations. In 95.5% of the patients subjected to pacemaker treatment no syncopes recurred. A relatively small proportion (19.5%) of the patients with unclarified syncopes continued to suffer from syncopes, the aetiology of which could not be determined during the 2-year follow-up period. This group of patients would require better diagnostic techniques, e.g. long-term ECGs over several days or long-term EEGs.