The Science of Uncertainty and the Art of Probability

Medicine is a science of uncertainty and an art of probability. — —William Osler (1849–1919) In this edition of Circulation , Spirito and coworkers present a retrospective study of a large cohort of patients with hypertrophic cardiomyopathy in which they compare the prognostic significance of neurally mediated (vasovagal) faints and unexplained syncope.1 Although neither symptom was significantly associated with sudden-death risk, subgroup analysis revealed that unexplained syncope was associated with a higher mortality in patients who had experienced their symptom within 6 months of their initial evaluation and in those aged <18 years. The authors conclude that recent unexplained syncope in all age groups “may justify consideration for prophylactic implantation of a cardioverter-defibrillator.” The challenge for clinicians is the translation of this message into everyday clinical management.Article p 1703 Syncope can be a difficult symptom to evaluate because patients may be unable to recall or accurately report their symptoms, have comorbidities such as epilepsy and diabetes mellitus that confound interpretation, or have more than 1 reason to faint. Nevertheless, a systematic approach to clinical assessment often identifies a probable mechanism (Table 1).2,3 The first and most important step is a careful history. For example, syncope that occurs after prolonged standing in a hot crowded environment or during the postprandial absorptive state or that is associated with nausea and vomiting is suggestive of neurally mediated (reflex) syncope. In contrast, syncope during exertion or preceded by palpitation or chest pain is more suggestive …