An unusual case of supraventricular tachycardia in a 64-year-old.

Abstract

To the Editor: Because individuals with Wolff-Parkinson-White (WPW) syndrome are often diagnosed and treated at a young age, it is rare to make an initial diagnosis of WPW in an elderly adult. A 64-year-old man who developed palpitations after surgery secondary to an atrioventricular (AV) reentrant tachycardia (AVRT) from underlying WPW syndrome is reported, and management of WPW in elderly adults is discussed. A 64-year-old man with a history of hypertension, panic disorder, and endovascular abdominal aortic aneurysm repair was admitted to vascular surgery for an endovascular prosthesis revision. On postoperative day 1, he developed a tachyarrhythmia as shown on electrocardiogram (ECG) (Figure 1A). He reported mild palpitations but denied any chest pain, shortness of breath, or lightheadedness during the episode. He was given intravenous metoprolol, and his tachyarrhythmia resolved. A cardiology consultation was requested for further evaluation. He denied having had any recent palpitations before admission and had no history of cardiac disease. His outpatient medications for his peripheral vascular disease and hypertension included aspirin, clopidogrel, and carvedilol. His preoperative ECG is shown in Figure 1B. On examination, he was afebrile and had a blood pressure of 104/96 mmHg, heart rate of 75 beats per minute (bpm), and a respiratory rate of 24 bpm with 97% oxygen saturation breathing ambient air. His heart rhythm was regular, without any murmurs or gallops. His jugular venous pressure was normal as estimated by bedside examination. He had no lower extremity edema, and his lungs were clear to auscultation. His metabolic panel showed potassium of 3.6 mg/mL (normal range 3.7–5.2 mg/mL), calcium of 7.8 mg/dL (normal range 8.9–10.2 mg/dL), and magnesium of 1.8 mg/dL (normal range 1.8–2.4 mg/dL). Complete blood count showed a white blood cell count of 5,840/μL (normal range 4.3–10.0/μL), a hematocrit of 24% (38–50%), and platelets of 45,000/μL (normal 150–400/μL). His ECG after receiving metoprolol is shown in Figure 1C. WPW syndrome is diagnosed according to the presence of preexcitation on ECG (a widened QRS complex with a slurred upstroke (delta wave) and a short PR interval) in the setting of symptoms, which can vary in presentation from mild palpitations and lightheadedness to syncope and sudden cardiac death. The accessory pathway(s) underlying the preexcitation can, under the right circumstances, initiate and maintain reentrant arrhythmias. This individual's tachyarrhythmia was a regular narrow complex rhythm with a ventricular rate of 164 bpm, with retrograde P-waves seen in the T-waves, consistent with AVRT. There were also T-wave inversions in leads I and aVL, and prominent ST depressions in the anterolateral (V3–V6) and inferior leads (II, III, aVF). The preoperative and post-beta-blockade ECGs are most revealing. Both show the classical findings of WPW pattern and support that the supraventricular tachyarrhythmia was orthodromic AVRT—with initial conduction down the AV node and back up to the atria through the bypass tract. The delta waves were less prominent (narrower QRS complex) at higher heart rates (Figure 1B,C), which presumably reflects higher sympathetic tone enhancing AV nodal in favor of bypass tract conduction. Q-waves were also present in leads I and aVL, consistent with a pseudolateral wall infarct pattern commonly seen with accessory pathways in the left lateral free wall.1 WPW pattern occurs in 0.1% to 0.3% of the total population, and 35% to 40% of individuals with the pattern are asymptomatic.2, 3 Because of early detection and treatment of symptomatic cases, it is rare to make an initial diagnosis in elderly adults. One study showed that only 7% of individuals with WPW were aged 60 and older.4 Moreover, the incidence of sudden cardiac death, usually from ventricular fibrillation, may occur at a rate of approximately 0.15% per patient-year in symptomatic individuals.5 In elderly adults, there is additional concern regarding their ability to tolerate tachyarrhythmias because of the greater prevalence of coexisting cardiac comorbidities. Although cardiac ablation is the treatment modality of choice in younger individuals and has comparable success rates in those aged 65 and older, it is associated with a higher rate of procedural complications in elderly adults (9% vs 1% in one small study).6 In this individual AV nodal blockers were initially used to control his rate, but had he developed atrial fibrillation or wide-complex tachycardia, these agents would have been avoided given the potential to precipitate an unstable arrhythmia by blocking AV nodal conduction and enhancing accessory pathway conduction. Procainamide, less commonly amiodarone, or if unstable, electric cardioversion would have been used in such a setting. He was offered ablation but elected to defer and was discharged home on a low-dose beta-blocker. Conflict of Interest: The authors have no financial or any other personal conflict to report. Author Contributions: Study concept and design: Li, Chen. Acquisition of subject and data, analysis and interpretation of data, preparation of manuscript, critical review and approval: all authors. Sponsor's Role: None.