A High-Level Athlete With Tachycardia-Induced Cardiomyopathy

Abstract

Background

Pediatric athletes with tachycardia and ventricular dysfunction are often assumed to have dilated cardiomyopathy or myocarditis, but a broad differential should be maintained.

Case Summary

An 18-year-old competitive athlete presents to the emergency room with tachycardia and chest pain. Electrocardiogram was thought to show high right-atrial tachycardia consistent with sinus tachycardia, and echocardiogram demonstrated diminished left ventricular systolic function without dilation. Viral myocarditis and cardiomyopathy genetic testing were negative. Further observation and workup demonstrated ectopic atrial tachycardia, which was treated, and the patient returned to sports.

Discussion

Tachycardia-induced cardiomyopathy is a rare, but reversible, cause of tachycardia and ventricular dysfunction. Exercise stress test can be useful in risk stratification. If returning to sport activity, an emergency action plan must be discussed with the patient and athletic training staff.

Take-Home Message

Tachycardia-induced cardiomyopathy can be a subtle diagnosis but should not be missed, as this disease can be reversible with appropriate treatment.

Visual Summary

Visual Summary.

Description of the Patient History and Take-Home Points From the Case

History of Presentation

The patient is a previously healthy 18-year-old competitive athlete who presented to the emergency room for tachycardia and chest pain, with associated nausea and lightheadedness. Prior to his presentation to the emergency room, he was noted to have heart rates ranging from 120 to 200 bpm in a nonexertional setting. The heart rate in the emergency room was 120 bpm, and 12-lead electrocardiogram (Figure 1A) was of high right-atrial origin, likely sinus tachycardia, thought to be secondary to hypovolemia. However, this tachycardia did not respond to fluid resuscitation, so cardiology was consulted, and a transthoracic echocardiogram was obtained demonstrating moderately diminished left ventricular (LV) systolic function. There were no wall motion abnormalities, troponin was normal, and the LV size was within normal range (left ventricular internal dimension in diastole 5.3 cm, Z-Score -0.5). He was subsequently transferred to the cardiology service for additional evaluation.

Take-Home Messages

• •The differential for tachycardia and ventricular dysfunction should include tachycardia-induced cardiomyopathy.
• •Tachycardia-induced cardiomyopathy is reversible if diagnosed and treated early.
• •An exercise stress test can assess arrhythmia at rest and with exertion, which can help inform decisions on safe competitive sports participation.

Figure 1.

Evolution of Atrial Tachycardia during Exercise Stress Test

(A) Patient's electrocardiogram at rest, demonstrating atrial tachycardia with long PR interval. (B) Patient's electrocardiogram at the start of the exercise test, demonstrating the transition from atrial tachycardia to normal sinus rhythm.

Past Medical History

None.

Differential Diagnosis

The initial differential diagnosis for this young athlete with LV systolic dysfunction and tachycardia included myocarditis, genetic dilated cardiomyopathy, coronary artery anomaly, hypertension-associated cardiomyopathy, tachycardia-induced cardiomyopathy (TIC), and hyperthyroidism.

Investigations

An infectious myocarditis workup, including adenovirus, cytomegalovirus, parvovirus, and enterovirus, were all negative. Troponin remained normal, as did labs measuring end-organ function and brain natriuretic peptide. Expedited exome sequencing was sent and found to be negative, multiple weeks later.

Management

The inappropriate nature of his tachycardia became apparent during the admission. The degree of tachycardia was out of proportion to his level of ventricular dysfunction and inconsistent with his compensated state. This raised the possibility of the high right atrial tachycardia (AT) to be ectopic AT from abnormal automaticity. Ivabradine and sacubitril/valsartan (Entresto) 24–26 mg were started during the hospitalization. He began to show brief breaks from AT on ivabradine, with underlying sinus rhythm rates averaging 50 to 60 bpm.

Cardiac magnetic resonance imaging was performed after starting on ivabradine and did not demonstrate edema or scarring, with an estimated LV ejection fraction of 52% during sinus beats. He remained in the cardiac center for 6 days, with intermittent runs of AT, but was discharged with normal function in sinus rhythm.

Outcome and Follow-Up

Entresto was increased to 49–51 mg BID at his first outpatient sports cardiology appointment. He continued to have recurrent breakthrough episodes of AT on a maximal dose of ivabradine. This led to intracardiac electrophysiology testing and mapping which identified focal AT from the anterolateral aspect of the body of the right-atrial appendage. Irrigated radiofrequency catheter ablation (CA) performed during this time achieved modification and attenuation of the arrhythmia substrate. He was started on nadolol and flecainide for interim control. Formal cardiopulmonary exercise testing was performed in the interim following his first CA and found resting AT, which converted to sinus rhythm during exercise, thought to be a result of the modified arrhythmia substrate (Figure 1B). Stress echocardiography did not demonstrate any wall motion abnormalities.

Given his negative stress test and recovered ventricular systolic function on echocardiography, he was cleared to return to competitive athletics. He was brought in for a second attempt at CA, and mapping identified a focal AT from the medial aspect of the body of right-atrial appendage. The arrhythmia focus was successfully eliminated using cryocatheter ablation. The most recent imaging studies demonstrate normal LV systolic function. He has remained asymptomatic while participating in high-intensity summer workouts with his team.

Discussion

This case demonstrates the differential diagnosis of ventricular dysfunction and tachycardia and highlights the subtlety of TIC. TIC is a chronic condition where persistent rapid heart rates can lead to ventricular dysfunction. TIC can easily be misdiagnosed as a primary dilated cardiomyopathy with resultant secondary arrhythmias or sinus tachycardia as a compensation for marginal cardiac output. TIC is rare but, as demonstrated in this case, reversible and therefore should always remain in the differential. Right-atrial appendage tachycardia is more prevalent in young male patients and is commonly associated with TIC.^1,2 This form of high right AT is known to masquerade as “sinus tachycardia” on a 12-lead electrocardiogram, and therefore, a high index of suspicion is required. It is important to recognize the “inappropriate” nature of this tachycardia so that effective therapeutic decisions can be made. They can be resistant to CA attempts, requiring repeat attempts and use of alternative energy sources.^3,4

Formal exercise stress testing can be helpful for risk stratification, after the diagnosis of TIC has been made. An arrhythmia that suppresses at higher heart rates can suggest a lower risk. This overdrive suppression of the arrhythmia is due to sympathetic stimulation and sinus node activation, which overtakes the slower ectopic atrial focus.⁵

As part of the shared decision-making process, the sports cardiology team worked jointly with his athletic training staff and physicians. Discussions included the availability of an automated external defibrillator during exercises, practices, and games, as well as having a teammate, staff member, or work-out partner assist in the event of an event. We instructed the patient that an automated external defibrillator needed to always be present for exercises, practices, and games. He also was instructed to work out with a partner, either a teammate or a staff member, who could assist if a sudden cardiac event occurred.

Conclusions

This case study emphasizes the importance of having a broad differential diagnosis when evaluating a patient with tachycardia and ventricular dysfunction. While dilated cardiomyopathy with compensatory sinus tachycardia or myocarditis is more common, TIC should remain on the differential. TIC can be reversible if diagnosed early. The patient with TIC can typically return to sports with shared decision-making, especially if the patient has a lower-risk arrhythmia that resolves with exercise.

Funding Support and Author Disclosures

The authors have reported that they have no relationships relevant to the contents of this paper to disclose.