Dr. Jarrard suggests that loop monitoring should replace 24-hour Holter monitoring in patients with syncope. The problem with this point of view is that a patient needs to be symptomatic while wearing a loop monitor for the test to provide any useful information. Because 85% of patients with a first episode of syncope will not faint again within the next 6 months [1], loop monitoring would be of no benefit in these patients. However, Holter monitoring can document background rhythm disturbances (such as sinus pauses or nonsustained bouts of ventricular tachycardia) that, although nondiagnostic, might prompt further evaluation and subsequent diagnosis. Loop monitoring has the most benefit in patients with relatively frequent bouts of syncope or palpitations.

Dr. Roda's suggestion that routine laboratory testing should be a part of the syncope workup is not supported by the literature. Anemia is not listed as a cause of syncope in most references, nor is hyponatremia, hypokalemia, or other such disorders. Population-based studies of patients with syncope have not documented the importance of routine laboratory tests [2]. We believe that a thorough history and physical examination, including measurement of orthostatic vital signs and, when indicated, a rectal examination, will alert the clinician to such abnormalities and prompt a more focused diagnostic evaluation.

Dr. Brody's elderly patient who had syncope in church and aortic valve disease [3] is a provocative case (we suspect that this is why Annals decided to publish it!). This patient had intensive cardiac evaluation followed by placement of a coronary stent and a permanent pacemaker, only to eventually present with gastrointestinal bleeding from colon cancer while receiving warfarin. Was the colon cancer missed, and would a complete blood count early on have helped to diagnose it? (In fact, it is hard to imagine that a complete blood count was not done before some of these invasive procedures.) One possible scenario would be that the patient was not anemic at the time of syncope, that the syncopal episode was due to cardiac ischemia or bradyarrhythmia, that the pacemaker and stent were appropriately placed, and that the colon cancer was incidentally discovered once the patient had received anticoagulation. More details about the nature of the patient's syncopal episodes would help sort this out (for example, were they sudden, exertional or positional, or associated with chest pain?), as would more information on the patient's presenting physical examination (for example, was pallor or orthostatic hypotension present?).