Takotsubo Syndrome and Complete Heart Block: A Diagnostic and Management Conundrum

Abstract

There is increasing evidence that Takotsubo cardiomyopathy behaves more like a highly variable and dangerous syndrome than an isolated cardiomyopathy. In this case report, we describe a case of Takotsubo cardiomyopathy complicated by complete heart block. We discuss the potential mechanisms for its etiology and examine the need for pacemaker placement.

Introduction

Stress cardiomyopathy (SCM) is a well-known cause of cardiomyopathy characterized by transient left ventricular (LV) systolic dysfunction in the absence of acute plaque rupture. First described in Japanese literature in 1990, it was given the name “Takotsubo cardiomyopathy (TTC)” for its resemblance to an octopus trap on left ventriculography. ¹ Stress cardiomyopathy disproportionately affects postmenopausal women, with The International Takotsubo Registry of 1750 patients reporting that nearly 90% of affected individuals are women with a mean age of 66.8 years. ² Most of the affected individuals experience a preceding emotional or physical stressor; however, up to 29% of patients have no predisposing trigger. ² Generally thought to be a relatively benign and reversible condition, newer literature has shed light on the various complications associated with significant morbidity and mortality, including but not limited to life-threatening arrhythmias, cardiogenic shock, and cardiac arrest. ³ Complete atrioventricular block (AV) block is one of the rarer complications of TTC, with 2 studies finding a prevalence of 2.2% and 2.8%, respectively (13.5% risk for any form of life-threatening arrhythmia).^4,5 In this case report, we describe a case of TTC complicated by complete AV block. We discuss the potential mechanisms for its etiology, as well as the management conundrum it presents.

Case

A 90-year-old woman presented to the emergency department with chest pain associated with exertion and emotional stress while at a family reunion which started 1 hour prior to arrival. She reported 10/10 chest pressure with radiation to the left shoulder, neck, and arm with associated shortness of breath. Prior to this event, the patient had great functional status and performed all activities of daily living without symptoms. On physical examination, the patient was diaphoretic, and auscultation revealed a regular, bradycardic rhythm with a II/VI holosystolic murmur that was loudest at the apex. She was afebrile with blood pressure of 104/58 mm Hg, heart rate of 40/minute, and oxygen saturation of 96% on ambient air.

Admission electrocardiogram (ECG; Figure 1) showed complete heart block characterized by AV dissociation with a narrow QRS junctional escape rhythm, atrial rate of 75/minute, and ventricular rate of 40/minute. Chest radiograph demonstrated no acute cardiopulmonary disease. Initial labs were significant for hemoglobin of 11.3 g/dL (reference: 12.0-16.0 g/dL), troponin of 0.14 ng/mL (reference: <0.04 ng/mL), and B-type natriuretic peptide of 230 pg/mL (reference: 0-100 pg/mL). All other labs were unremarkable.

Figure 1.

Twelve-lead electrocardiogram showing complete heart block with junctional escape rhythm, atrial rate of 75/minute, and ventricular rate of 40/minute.

The patient had a medical history significant for lung cancer status post chemotherapy, radiation, and right middle lobectomy; resistant hypertension; hyperlipidemia; well-controlled type II diabetes; well-controlled chronic obstructive pulmonary disease; and tobacco use disorder with a 30 pack-year smoking history. Medications included valsartan, amlodipine, hydralazine, rosuvastatin, fluticasone-salmeterol, and metformin.

Given the patient’s age and risk factors, acute coronary syndrome and age-related degenerative conduction disease were highest on the differential upon presentation. Other differentials considered were infiltrative diseases such as amyloidosis, as well as TTC and lyme disease.

The patient was subsequently admitted to the cardiac care unit for the diagnosis of complete heart block and non-ST-elevation myocardial infarction (NSTEMI). Intravenous dopamine and unfractionated heparin were started for the treatment of bradycardia and NSTEMI. After initiating intravenous dopamine infusion, ECG (Figure 2) demonstrated the rhythm converted to 2:1 AV heart block, atrial rate of 90/minute, and ventricular rate of 42/minute.

Figure 2.

Twelve-lead electrocardiogram showing 2:1 atrioventricular heart block with ventricular rate of 42/minute and atrial rate of 90/minute.

Troponin continued to trend up and peaked at 2.87 ng/mL. Transthoracic echocardiogram (Figure 3) was significant for an ejection fraction of 41%-45%, mild mitral regurgitation, and evidence of regional wall abnormalities, mid and distal anteroseptal, apical, apical lateral, and inferoapical akinesia, consistent with TTC.

Figure 3.

Echocardiogram showing symmetrical regional wall abnormalities extending into the apical inferior and lateral wall with hypokinesia of the LV.

The patient underwent left heart catheterization to rule out ischemic heart disease. There was no significant obstructive coronary disease found. Heparin and dopamine were discontinued and the patient had a transvenous pacer placed to bridge until placement of a dual-chamber permanent pacemaker (PPM). Her hospital course remained uneventful, and the patient was discharged with outpatient cardiology follow-up.

At 6 months the patient did not have any hospital readmissions, and a repeat echocardiogram demonstrated recovery of ejection fraction.

Discussion

Takotsubo cardiomyopathy, the “broken heart” disease, has historically been thought of as a relatively benign and reversible condition. However, new data analysis suggests that while it is reversible, it may not be so benign. A 2018 International Consensus Document published in the European Heart Journal explained that rates of cardiogenic shock and death are similar to acute coronary syndrome, and around 20% of patients with TTC experience life-threatening complications in the acute phase of the disease. ³ Due to this, the authors stated that TTC should actually be renamed Takotsubo syndrome. The inciting factor for this syndrome is classically a physical or emotional stimulus that causes a catecholamine surge which acts as a myocardial toxin. The extensive list of possible life-threatening complications includes but is not limited to cardiomyopathy, LV outflow tract obstruction, LV thrombus, cardiogenic shock, and various arrhythmias. ³

Our patient had one of these life-threatening arrhythmias, as she presented with complete AV block and was diagnosed with TTC after classic echo findings and unremarkable coronary catheterization. The exact mechanism of complete AV block in TTC is not known, but there are multiple theories that have been proposed. One theory is that catecholamine surge causes spasm of micro branches of coronary arteries, mimicking ischemia or causing a reflex increase in vagal tone. ⁶ Another theory is that the myocardial edema thought to be responsible for LV dysfunction may also play a role in AV dysfunction.^3,7 However, this brings up the conundrum to why LV dysfunction is reversible, but AV dysfunction is thought to be often permanent. A new theory is based on cardiac magnetic resonance imaging findings that found that TTC patients who developed malignant arrhythmias had a higher incidence of subtle, diffuse fibrosis/micronecrosis. ⁴ This in theory could mean the pathology of AV dysfunction is secondary to an accelerated degenerative/infiltrative disease process.

Despite all these possible mechanisms of TTC causing AV dysfunction, it is vital to understand that TTC and complete AV block is most often a “chicken or the egg” phenomenon. The demographics of these patients are those that are at baseline high risk of degenerative conduction disease with roughly two-thirds of patients greater than 70 years of age. ⁴ It is extremely difficult to prove there is no underlying degenerative conduction disease in this patient population. Given our patient’s age, she likely had some component of degenerative conduction disease. The abrupt onset of TTC may have caused an acute acceleration of her underlying senile conduction disease, leading to the development of complete heart block. On the other hand, there have been case reports that have proved via temporal relationship that a complete AV block can cause TTC. ⁸ It is due to this lack of clarity that around 75% of these patients receive a PPM. ³ On the other hand, one case review found that 4 of 24 cases had resolution of the block, so implantation of a PPM was not performed. ⁹ Permanent pacemaker placement is notably not a benign procedure with complications occurring in approximately 10% of cases. Among these potential complications is the procedure itself causing TTC. ⁹ More research is required to investigate the permanence of AV blocks caused by TTC to guide the need for PPM placement.

Conclusion

Complete heart block is one of the many life-threatening complications that can occur in the setting of TTC. Often the complete heart block is a “chicken or the egg” phenomenon where determining the etiology is challenging, if not impossible. Furthermore, there are limited data on the permanence of TTC-implicated AV blocks, which has led to a lack of evidence-based guidelines regarding need for PPM placement. Currently, decisions regarding PPM placement should be made on an individual basis with shared decision-making until further research is performed.