Polymyositis-Induced Atrial Flutter: A Rare and Unexpected Arrhythmia in an Idiopathic Inflammatory Myopathy

Abstract

We describe a 28-year-old Caribbean-Black female with polymyositis-associated atrial flutter during an acute flare episode for which she was successfully managed with guideline-directed medical therapy and noninvasive positive pressure ventilation. The clinician should be cognizant of this rare association, especially in young patients who present with symptomatic arrhythmias and chronic, preexisting idiopathic inflammatory myopathies.

Introduction

The systemic inflammatory response is robustly implicated in cardiovascular diseases and arrhythmogenesis in rheumatologic conditions.^1,2 Idiopathic inflammatory myopathies (IIMs) are a heterogeneous subgroup of autoimmune disorders characterized by immune-mediated muscle damage, namely dermatomyositis, polymyositis (PM), inclusion body myositis, and necrotizing myopathy.^3,4 PM is an autoimmune and chronic inflammatory myopathy characterized by symmetrical proximal muscle weakness due to the involvement of endomysial layers of skeletal muscles.^5-7

With respect to IIMs, conduction disorders are generally more prevalent than rhythm disturbances, notably during disease flares.^8,9 Myocardial inflammation and fibrosis play pivotal roles, with sequelae of electro-anatomical remodeling. Additionally, chronic inflammation can exacerbate autonomic dysfunction, with accentuated sympathetic overactivation and attenuated parasympathetic function. Autoantibody-mediated and drug-induced arrhythmias are also encountered in patients with IIMs.^5,10,11

We describe a 28-year-old Caribbean-Black female with PM-associated atrial flutter (AFL) during an acute flare episode for which she was successfully managed with guideline-directed medical therapy (GDMT) and noninvasive positive pressure ventilation (NIPPV). The clinician should be cognizant of this rare association, especially in young patients who present with symptomatic arrhythmias and chronic, preexisting IIMs.

Case Presentation

A 28-year-old Caribbean-Black female with a documented history of PM for the previous 2 years, managed with prednisone 5 mg daily, presented to the emergency department with a 2-day episode of typical angina and progressive, exertional dyspnea. She also reported a symptom-complex of dysphagia, hoarseness, and palpitations without presyncope or overt syncope. These symptoms significantly impacted her ability to perform activities of daily living, including independent ambulation and personal hygiene. Of note, her past medical history was only positive for her relatively recent PM diagnosis, for which she was being managed by a rheumatologist. She denied illicit drug use, tobacco use, or significant alcohol consumption. Her family history was remarkable for a maternal aunt with systemic lupus erythematosus. She did not report any recent infection or ill contacts. She denied the use of any complementary and alternative medications or pertinent travel and pet history. She maintained her usual routine self-care with respect to diet and physical activity prior to the onset of this symptomatology.

Upon presentation, her vital signs included a blood pressure of 176/123 mm of mercury, a heart rate of 145 beats/minute, a respiratory rate of 28 breaths/minute with an oxygen saturation of 98% on 5 L of oxygen via a non-rebreather mask, and a temperature of 37.0 °C, which was afebrile. The patient was alert and oriented, with several identified focal neurological deficits. Medical Research Council strength scores for hip extensors, flexors, adductors, abductors, shoulder extension, flexion, external rotation, and elbow flexion and extension were three-fifths bilaterally. The cardiovascular examination revealed soft heart sounds (S₁ and S₂) without additional sounds or murmurs. Her jugular venous pulse was not elevated, and there was no sacral or pedal edema. Her apical pulse was not displaced with a normal character. The respiratory examination revealed bilateral vesicular breath sounds without wheezing or crackles. An initial 12-lead electrocardiogram demonstrated AFL at a rate of 160 beats/minute. There was a negative “sawtooth” pattern of flutter waves in the inferior leads, with normal QRS complex morphology and normal axis (Figure 1A). Urgent blood and urine investigations were negative for toxicology and pregnancy. Rapid human immunodeficiency virus and severe acute respiratory syndrome-coronavirus-2 antigen tests were also negative.

Figure 1.

The patient’s 12-lead ECGs. (A) The patient’s admission ECG demonstrated typical AFL with classic negative sawtooth “flutter waves” in the inferior leads. (B) The patient’s postpharmacologic cardioversion ECG demonstrates sinus tachycardia with subtle nonspecific ST-T changes. AFL, atrial flutter; ECGs, electrocardiograms.

The patient was immediately admitted to the adult intensive care unit, where she received NIPPV, intravenous fluid resuscitation (normal saline 0.9% at 150 cm³/hour), high-dose intravenous corticosteroids (hydrocortisone 200 mg every 8 hours), and intravenous metoprolol 5 mg every 6 hours and intravenous amiodarone 1 mg/minute for rate and rhythm control.^12-14 Despite her CHA₂DS₂-VASc score being calculated as 1, prognosticating a low risk of cerebrovascular events, she was therapeutically anticoagulated with a heparin infusion in the acute clinical scenario. ¹³ The erythrocyte sedimentation rate was elevated at 77 units/hour (normal range <20 units/hour). Creatine kinase levels were mildly elevated to 323 units/L (normal range 22-198 units/L). Thyroid function and other routine tests, including high-sensitivity cardiac troponins and d-dimer, were normal.

During her brief hospitalization in the ICU, she clinically stabilized within 48 hours with restoration of normal sinus rhythm (Figure 1B). She was transitioned to oral prednisone 60 mg daily and bisoprolol 2.5 mg daily, without long-term oral anticoagulation and was de-escalated to the cardiology ward. She was further monitored for an additional 48 hours with an inpatient rheumatology consultation and was subsequently discharged with a routine follow-up appointment with cardiology scheduled for one week.

Discussion

Typical AFL is a cardiac arrhythmia characterized by a counter-clockwise macro-reentrant circuit that encircles the tricuspid annulus and traverses the cavo-tricuspid isthmus (CTI).^15,16 This is electrocardiographically reflected as sawtooth “flutter” waves in the inferior leads. ¹⁷ A clockwise propagation is referred to as “reverse typical AFL,” whereas “atypical” AFL occurs in a non-CTI region.^18,19 Atrial fibrillation and AFL are now considered the most prevalent, persistent arrhythmia, largely attributed to the globally aging population.^20,21 They both pose incipient risks of major adverse cardiovascular events (MACE), such as embolic stroke and chronic heart failure.^22,23 Generally, AFL in the younger population was more associated with patients with structural or congenital heart disease; however, its incidence has risen due to higher rates of obesity, coupled with sedentary lifestyles, as well as worsening drug abuse.^19-21 Autoimmune diseases in young adults have also increased in prevalence and can be potentially burdensome with respect to morbidity and quality of life. ²⁴ Their maladaptive immune response may lead to arrhythmogenesis through an inflammatory milieu characterized by oxidative stress, apoptosis, and fibrosis.^7,25,26

PM can be histopathologically distinguished from inclusion body myositis due to the presence of intracytoplasmic inclusion bodies as well as from dermatomyositis due to perimysial infiltrates of CD4 cells and B lymphocytes. In PM, a critical disease pathway involves the accumulation of endomysial CD8+ T-cells, which form CD8+/MHC-I complexes. These cytotoxic T-cells secrete perforin granules, resulting in muscle fiber lysis and necrosis. Furthermore, CD4+ T-cells, macrophages, and dendritic cells release various pro-inflammatory cytokines, including interleukin-1, -6, -15, and -18, as well as tumor necrosis factor-α and type I interferons, inducing a vicious cycle. ²⁷ Additionally, the deposition of immune complexes can activate the body’s complement system. ¹⁰ This inflammatory cascade, characterized by the activation of fibroblasts, results in excessive myocardial collagen deposition and interstitial fibrosis.^2,9,28 This pathophysiology can lead to alterations in ion channel function, disrupted intracellular calcium handling, and neurohormonal activation, all of which are major contributory factors for cardiac arrhythmias and channelopathies.^10,25

PM is often associated with other autoimmune diseases and comorbidities such as hypertension, diabetes, and coronary artery disease, which can further accentuate the risk of AFL.^26,29 It also prognosticates a circa 10% mortality rate, especially in the subgroup of patients with cardiac dysfunction or neoplasia.^7,30 While managing an acute flare of PM, crucial objectives are to mitigate endogenous inflammation while attenuating morbidity and mortality with standard-of-care resuscitation guidelines. ⁶ In achieving these goals, glucocorticoids remain the cornerstone of therapy, with a standard oral prednisone dosage of 1 mg/kg of body weight. This is often administered in high doses, reaching up to 100 mg/day, with the majority of patients responding. ⁷ NIPPV has emerged as a vital and secure airway option for managing acute respiratory failure, as demonstrated in our patient. ³¹ Additionally, a regimen of low-dose beta-blockade and amiodarone was successfully employed to swiftly achieve rate and rhythm control in the patient, precluding the need for synchronized cardioversion, given her relative hemodynamic stability. Long-term anticoagulation was deemed unnecessary as the patient’s CHA₂DS₂-VASc score was 1, and restoring rhythm control was prioritized. ¹³

This case had some interesting aspects, as it illustrated a rare arrhythmia in a young female patient with a relatively new IIM diagnosis who presented with an acute flare and respiratory failure. As previously alluded to, this is a key learning point: a clinician must consider the etiology of the AFL being linked to PM and employ multipronged management strategies that include rate and rhythm control, as well as potential anticoagulation and NIPPV, along with high-dose intravenous steroids. Due to her swift resolution of symptoms and restoration of normal sinus rhythm, escalation of pharmacotherapeutics, such as immunomodulators, intravenous immunoglobulins, and biologics, was not necessary. ⁷ PM, being a chronic condition, is also associated with a negative prognosis in patients who are female, older, or of Black ethnicity, with either systemic or refractory involvement. Our patient possessed 3 of these risk factors (female, Black ethnicity and systemic involvement of respiratory muscles, and AFL) and was extensively counseled with respect to crucial issues such as future pregnancy, malignancy risk, acute coronary syndromes, and lifestyle modification, including diet and physical therapy.^7,32,33

Conclusion

We describe a 28-year-old Caribbean-Black female with a diagnosis of suspected PM-AFL. The patient received GDMT for the PM flare and associated arrhythmia. This case highlights the importance of considering atypical etiologies, such as cardiac arrhythmias, when evaluating palpitations and shortness of breath on exertion in young adults with autoimmune conditions. Early recognition and appropriate treatment of these conditions are essential for optimizing patient morbidity and mortality.