Is an underlying cardiac condition causing your patient’s palpitations?

Physical examination clues, and the utility of vagal maneuvers

Although most patients in whom palpitations are the presenting complaint are, in fact, asymptomatic during clinical assessment, cardiovascular examination can assist in diagnosing the arrhythmia or structural heart disease:

• Resting bradycardia increases the likelihood of a clinically significant arrhythmia (LR = 3; 95% CI, 1.27-7.0).¹¹
• A murmur, such as a midsystolic click or holosystolic murmur, detected during the cardiac exam can indicate mitral valve prolapse; a holosystolic murmur, exacerbated upon performing a Valsalva maneuver, suggests hypertrophic cardiomyopathy.
• Visible neck pulsations detected during assessment of the jugular venous pressure, known as cannon atrial (cannon A) waves, reflect abnormal contraction of the right atrium against a closed tricuspid valve during AV dissociation. Cannon A waves have an LR of 2.68 (95% CI, 1.25-5.78) for predicting AVNRT.⁴

Vagal nerve stimulation. In the rare circumstance that a patient complaining of palpitations is symptomatic during assessment, several tachycardias can be detected with the use of vagal maneuvers. Interruption of the tachycardia during carotid massage suggests a tachycardia involving the AV junction (AVNRT), whereas only a temporary pause or reduction in frequency is more common in atrial flutter, AF, and atrial tachycardias. Carotid massage has no effect on the presentation of ventricular arrhythmias.¹⁰

Diagnostic testing and the role of ambulatory monitoring

Electrocardiography. All patients with palpitations should have a 12-lead EKG, which may provide diagnostic clues (TABLE 2¹⁰).

Ambulatory monitoring. When the EKG is nondiagnostic, ambulatory cardiac monitoring has an established role in the diagnosis of recurrent palpitations. In a small study of patients presenting with palpitations to a general practitioner, the deduction of those practitioners was wrong more than half the time when they predicted a ≤ 20% chance of an arrhythmia based on the history, physical exam, and EKG alone¹³—emphasizing the importance of ambulatory monitoring in patients with recurrent palpitations.

A comprehensive history should also evaluate for risk factors and symptoms of cardiac disease (chest pain, dyspnea, diaphoresis, lightheadedness, syncope).

Which monitoring system is most suitable depends on symptom frequency, availability, cost, and patient competence. Twenty-four- to 48-hour Holter monitoring can be used in cases of frequent (eg, daily) palpitations. An automatic external loop recorder can be used for less frequent (eg, every 30 days) symptoms. Most ambulatory EKG is now automatic, and therefore does not require patient activation; older manual systems require patient activation during symptoms.

Two weeks of ambulatory EKG have proved sufficient for determining that there is a cardiac basis to palpitations. The diagnostic yield of ambulatory EKG is highest during Week 1 (1.04 diagnoses per patient), compared to Week 3 (0.17 diagnoses per patient).¹⁴

Implantable loop recorders are placed subcutaneously to provide EKG monitoring for approximately 3 years. They are better suited for diagnosing infrequent palpitations. The diagnostic yield of an implantable loop recorder over the course of 1 year for the detection of an arrhythmia is 73%, compared to 21% for a 24-hour Holter monitor, electrophysiology studies, and 4 weeks of an external loop recorder.¹⁵ Implantable loop recorders are often reserved for patients with palpitations associated with unexplained recurrent syncope.¹⁵

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