An event recorder would be appropriate to evaluate this patient's episodic symptoms of palpitations and lightheadedness. The evaluation and identification of arrhythmias can be challenging because of their intermittent nature; the modality used depends on the frequency and nature of the symptoms. In patients with infrequent symptoms, event recorders are the most effective means of obtaining rhythm information around the time of the symptoms. Event recorders record electrocardiographic (ECG) tracings only when activated by the patient and are more useful for infrequent symptoms. Two types of event recorders are used. A patient-triggered recorder is an external device without leads that is held to the chest and triggered by the patient when symptoms occur. The advantage of this device is the lack of electrode leads, making it more comfortable and convenient; however, no preceding rhythm is saved when the device is triggered. When the patient activates a looping event recorder, a permanent recording is created that includes several seconds of the presymptom rhythm, which is useful in patients with syncope.

In patients in whom pathologic structural heart disease is suspected, transthoracic echocardiography provides noninvasive, quantitative evaluation of cardiac size and function, valve morphology and function, pericardial disease, pulmonary artery pressures, and proximal great vessels. Physical examination findings in patients with structural disease include signs of heart failure and abnormal cardiac auscultation. In this patient, there is no evidence of structural heart disease by either history or examination, so an echocardiogram is not warranted.

Exercise ECG stress testing allows diagnosis of exercise-related arrhythmias, as well as assessment of the impact of the arrhythmia on blood pressure. The patient does not describe exercise-related symptoms, and an exercise stress test is not indicated.

Ambulatory ECG monitors record continuous rhythms and can be useful when patients have frequent, usually daily, symptoms. Monitors are usually worn for 24 or 48 hours. Patients are encouraged to perform their normal activities while wearing the monitor. Patients keep a symptom diary or trigger a marker on the continuous reading that correlates with symptoms. Ambulatory ECG monitors can also be useful to detect asymptomatic arrhythmias, such as asymptomatic atrial fibrillation. This patient's symptoms occur about once a week, and a 24- or 48-hour ambulatory monitoring period is likely to miss the symptomatic episodes.