CHAPTER 81: APPROACH TO THE PATIENT WITH CARDIAC ARRHYTHMIAS

INTRODUCTION

Cardiac arrhythmias are common in clinical practice,¹ yet their diagnosis and evaluation can be challenging because of diverse presentations² and clinical impact, which can range from minor to potentially life-threatening. The evaluation must be comprehensive, but should focus initially on a detailed history of episodes and relevant comorbidities, and on electrocardiogram (ECG) documentation of index episodes. Cardiac arrhythmias may present with cardiovascular symptoms such as palpitations or dizziness, but may also present with symptoms from secondarily affected organs such as cryptogenic stroke or peripheral thromboembolism. Important arrhythmias may also be asymptomatic,³ so that the clinician must maintain a high index of suspicion for these conditions, particularly in individuals with structural heart disease or a family history of unexplained syncope. The purpose of this chapter is to provide a general approach to evaluate patients with arrhythmias, and those who require arrhythmia screening. Other chapters of this textbook will detail the management of specific arrhythmias.

HISTORY

The clinical history is often pivotal in deciphering cardiac arrhythmias. It is important to recognize that arrhythmia symptoms can be diverse and may include palpitations, lightheadedness, chest “discomfort,” heart failure, fatigue, or neurological symptoms such as amaurosis fugax. The symptom complex in each individual should be defined for (1) onset, particularly whether sudden or gradual; (2) associated symptoms; (3) potential triggers of episodes; (4) the duration and frequency of episodes; (5) temporal patterns (eg, “Are they improving or not?”); (6) the effect of interventions such as Valsalva or vagal maneuvers such as coughing or swallowing ice,⁴ which may terminate some arrhythmias; (7) the effect of prescribed therapy; and (8) family history of similar symptoms, cardiac disease, unexplained syncope, or sudden death.

The history should be pertinent while also considering potential predispositions. For instance, a past history of rheumatic valve disease or thyrotoxicosis may cause atrial fibrillation (AF) in a patient with intermittent palpitations or cryptogenic stroke; a history of myocardial infarction (MI) may cause ventricular arrhythmias⁵ in a patient with palpitations or near-syncope; while medications that are known to prolong the QT interval or may produce hypotension may explain dizzy spells. Although alcohol⁶ is linked with AF in some patients, this is inconsistent. The link between caffeine⁷ and arrhythmias is less clear, and perhaps more clear for sinus tachycardia than supraventricular tachycardias (SVTs). Neither alcohol nor caffeine is clearly linked with paroxysmal SVTs or sustained ventricular tachycardias (VTs). Patients with AF and comorbidities such as obstructive sleep apnea or morbid obesity should be identified a priori, because they respond less well to traditional therapy⁸ and may require risk factor modification⁹ or therapy tailored to specific localized substrate mechanisms, such as rotors.¹⁰ Careful attention to descriptions by the patient and accompanying individuals, focused on the items above, provide critical clues to decipher an arrhythmic etiology and guide management.

In evaluating the plan of ...