Blood norepinephrine/epinephrine/dopamine measurements in 108 patients with takotsubo syndrome from the world literature: pathophysiological implications

Left ventricular outflow tract obstruction/hypertrophic cardiomyopathy/takotsubo syndrome: A new hypothesis of takotsubo syndrome pathophysiology

The pathophysiology of TTS is still elusive. This viewpoint proposes that TTS is an acute coronary syndrome, engendered by an ASNS/catecholamine-induced LVOTO, which results in an enhanced wall stress and afterload-based supply/demand mismatch, culminating in a segmental myocardial ischemic injury state, in susceptible individuals. Such individuals are felt to be particularly women with chronic hypertension, known or latent HCM, or non-HCM segmental myocardial hypertrophy, and certain structural abnormalities involving the LV and the MV apparatus. Recommendations are provided to explore further this hypothesis, while maintaining our focus on all other advanced TTS pathophysiology hypotheses for all patients, or those who do not experience LVOTO, men, the young, and patients with reverse, mid-ventricular, or right ventricular TTS, in whom more prolonged hyperadrenergic stimulation and/or larger amounts of blood-ridden catecholamines, segmental particularities of cardiac innervation and/or density of α-, and β-adrenergic receptors, pheochromocytoma, neurological chronic or acute comorbidities/catastrophies, coronary epicardial/microvascular vasospasm, and CMD.

Coronary microvascular dysfunction in patients with Takotsubo syndrome

BACKGROUND

The pathophysiology of Takotsubo syndrome (TTS) remains incompletely understood. While coronary microvascular dysfunction (CMD) is a potential pathophysiologic mechanism, evidence is limited.

OBJECTIVES

We sought to evaluate CMD in patients with TTS.

METHODS

Consecutive patients diagnosed with TTS were included and underwent coronary angiography with invasive microvascular function evaluation, including fractional flow reserve, Coronary Flow Reserve (CFR), Index of Microcirculatory Resistance (IMR), and Resistive Reserve Ratio (RRR). Patients had an echocardiography evaluation during their index admission and at approximately 6 weeks.

RESULTS

Thirty patients were included (mean age 74 ±9, 90 % female). Twenty-five patients (83 %) had at least one abnormal coronary microvascular function parameter. Abnormal parameters included CFR<2.5 in 20 patients (67 %), IMR>25 in 18 patients (60 %), and RRR<3.5 in 25 (83 %). Longer time from symptoms to angiography correlated with a higher CFR (r = 0.51, P<0.01), and had an area under the receiver operating characteristic curve of 0.793 (95 % CI 0.60-0.98) for pathologic CFR. Patients with emotional trigger had a lower rate of pathologic IMR compared with non-emotional trigger (36 % vs 81 %, p = 0.01). Follow up echocardiography performed at a median of 1.5 months (IQR 1.15-6) showed an improvement in left ventricular ejection fraction for all patients (from mean of 40 % to 57 %).

CONCLUSION

CMD was present in most patients with TTS. The role of microvascular function in TTS may vary according to the clinical presentation and RRR may be more sensitive for the diagnosis of CMD in TTS.

Frequent POCUS and auscultation for an earlier diagnosis of takotsubo syndrome and unraveling of its pathophysiology: The possible crucial role of LVOTO

There is ample literature associating LVOTO with hypertension, AMI, LV hypertrophy, sigmoid septum, HCM, and TTS, particularly in midde aged/elderly/postmenopausal women, suggestive of a causal role for LVOTO in the pathophysiology of TTS. Although there is significant evidence that TTS is triggered by a sudden autonomic sympathetic nervous system surge and/or elevated blood-ridden catecholamines, the exact pathophysiologic trajectory leading to the clinical expression of the disease is still being debated. This review expounds on the possibility that LVOTO is a causal early component of this trajectory, and proposes that TTS is a malady within the broad spectrum of the myocardial ischemic injury/stunned myocardium states. The postulated underlying mechanism by which LVOTO causes TTS is a sudden abterload rise, with resultant oxygen/energy supply/demand mismatch, leading to a transient myocardial ischemia/injury myocardial stunning state. This needs to be explored painstakingly, and this review includes some suggestions for such undertaking. Ellucidation of the pathophysiology of TTS, and possible proof about a mechanistic role of LVOTO, may ensure that our current pharmacological and device panoply is adequate for the management of TTS.

Pheochromocytoma leading to Takotsubo and Ogilvie syndrome, a pathophysiological triad

Takotsubo syndrome (TTS) is a transient left ventricle dysfunction usually caused by a stressful trigger (emotional or physical). We report the case of a 77 year-old female patient who presented with TTS caused by a pheochromocytoma, a catecholamine-producing neuroendocrine tumour. Diagnosis was facilitated by acute kidney injury prompting renal ultrasound, recurrence of TTS and symptoms of episodic palpitations, profuse sweating and labile blood pressure. Furthermore, during her hospitalisation the patient also developed an Ogilvie syndrome, an acute colonic pseudo-obstruction, due to the catecholamine-excess. Treatment consisted of betablocker and angiotensin-converting enzyme inhibitor for TTS, neostigmine for Ogilvie syndrome, in combination with alpha-blocker and surgical removal of the tumour after recuperation of left ventricular function and colonic pseudo-obstruction. To our knowledge, this is the first case report of the pathophysiological triad of pheochromocytoma leading to Takotsubo and Ogilvie syndrome in a single patient.

Takotsubo Syndrome and Sudden Cardiac Death

Takotsubo syndrome (TTS), triggered by intense emotional or physical stress, occurring most commonly in post-menopausal women, presents as an ST-elevation myocardial infarction (MI). Cardiovascular complications occur in almost half the patients with TTS, and the inpatient mortality is comparable to MI (4-5%) owing to cardiogenic shock, myocardial rupture, or life-threatening arrhythmias. Thus, its prognosis is not as benign as previously thought, as it may cause mechanical complications (cardiac rupture) and potentially lethal arrhythmias and sudden cardiac death (SCD). Similar to MI, some patients may perish before reaching the hospital due to out-of-hospital cardiac arrest; this may lead to underestimation of the actual SCD risk. Furthermore, after discharge, some patients may develop late SCD and/or TTS recurrence that may result in SCD. There are risk factors for SCD in TTS patients, such as severe/persistent QT-interval prolongation inciting torsade-de-pointes, other ECG abnormalities (diffuse giant negative T-waves, widened QRS-complex), bradyarrhythmias, comorbidities, concurrent obstructive coronary artery disease or vasospasm, male gender, older age, severe left ventricular dysfunction, and use of sympathomimetic drugs. All these issues are herein reviewed, case reports/series and data from large cohort studies and meta-analyses are analyzed, risk factors are tabulated, and proarrhythmic effects and management strategies are discussed and pictorially illustrated.

Takotsubo Cardiomyopathy and β-Blocker Poisoning: A Case Report

β-blocker poisoning is frequently observed because of its primary use for the treatment of cardiovascular diseases. The management of β-blocker toxicity is dependent on the cardiovascular response and the severity of presentation. The present study describes the case of a patient with combined drug intoxication, β-blocker, digoxin, benzodiazepines, acetaminophen and opiates in a suicidal attempt. A 63-year-old female was found somnolent and in a confused state at her residence following intentional poly-drug ingestion. Upon presentation, she was found to be hemodynamically unstable and was thus treated with vasopressors. The toxicological screening performed upon presentation was positive for polydrug ingestion. On day 3, the patient developed chest pain and ST-segment elevation in anterior leads, while transthoracic echocardiographic assessment disclosed a non-dilated left ventricle with moderate dysfunction and akinesia of the apex. Coronary angiogram revealed normal coronary arteries and, subsequently, the diagnosis of Takotsubo cardiomyopathy (TTC) was suspected. Supportive treatment was initiated with favorable evolution and left ventricular ejection fraction normalization. The management of hemodynamic instability with vasopressors should be judiciously administered in the treatment of β-blocker poisoning, in view of the adverse effects on cardiac functions, including stress cardiomyopathy.

"Obesity paradox" and takotsubo syndrome

Background

An "obesity paradox" has been reported in patients with hypertension and heart failure, in which obese patients fare better than patients with normal-weight. The purpose of this study was to determine whether there is an "obesity paradox" in patients with takotsubo syndrome (TTS).

Methods

The prevalence of obesity in databases/registries of patients with TTS was compared to the prevalence of obesity in world general populations. Obese patients with TTS were explored regarding the stress triggers precipitating the illness, hospital outcome, and post-discharge readmission. Finally, the literature on the "obesity paradox" was explored to understand how it could be applied to TTS.

Results

A prevalence of obesity of ∼10-11% has been reported in large cohorts of patients with TTS, which represents 1/3 to ¼ of the prevalence reported in worldwide general populations, suggesting that, normal-weight than obese individuals, are more predisposed to develop TTS, with the latter nevertheless also suffering TTS, when triggered by enormous physical stresses. Obese patients with TTS are likely to have milder hospital outcomes, lower mortality, and lower rate of early readmission. A greater sympathetic nervous system (SNS) response in a number of hyperadrenergic states in normal-weight than obese patients, may explain findings in patients with TTS.

Conclusions

An "obesity paradox" has been identified in patients with TTS. Reporting on body mass index and other markers of obesity in patients with TTS, and implementing some recommendations on monitoring noninvasively the SNS in patients with TTS, may solidify that obesity has a preventive/ameliorating effect for TTS development and its clinical course.

Dopamine D1/D5 Receptor Signaling Is Involved in Arrhythmogenesis in the Setting of Takotsubo Cardiomyopathy

Background

Previous studies suggested involvement of non-ß-adrenoceptors in the pathogenesis of Takotsubo cardiomyopathy (TTC). This study was designed to explore possible roles and underlying mechanisms of dopamine D1/D5 receptor coupled signaling in arrhythmogenesis of TTC.

Methods

Human-induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) were challenged by toxic concentration of epinephrine (Epi, 0.5 mM for 1 h) for mimicking the catecholamine excess in setting of TTC. Specific receptor blockers and activators were used to unveil roles of D1/D5 receptors. Patch clamp, qPCR, and FACS analyses were performed in the study.

Results

High concentration Epi and two dopamine D1/D5 receptor agonists [(±)-SKF 38393 and fenoldopam] reduced the depolarization velocity and prolonged the duration of action potentials (APs) and caused arrhythmic events in iPSC-CMs, suggesting involvement of dopamine D1/D5 receptor signaling in arrhythmogenesis associated with QT interval prolongation in the setting of TTC. (±)-SKF 38393 and fenoldopam enhanced the reactive oxygen species (ROS)-production. H₂O₂ (100 μM) recapitulated the effects of (±)-SKF 38393 and fenoldopam on APs and a ROS-blocker N-acetylcysteine (NAC, 1 mM) abolished the effects, suggesting that the ROS-signaling is involved in the dopamine D1/D5 receptor actions. A NADPH oxidases blocker and a PKA- or PKC-blocker suppressed the effects of the dopamine receptor agonist, implying that PKA, NADPH oxidases and PKC participated in dopamine D1/D5 receptor signaling. The abnormal APs resulted from dopamine D1/D5 receptor activation-induced dysfunctions of ion channels including the Na⁺ and L-type Ca²⁺ and I_Kr channels.

Conclusions

Dopamine D1/D5 receptor signaling plays important roles for arrhythmogenesis of TTC. Dopamine D1/D5 receptor signaling in cardiomyocytes might be a potential target for treating arrhythmias in patients with TTC.

Plasma catecholamine levels in the acute and subacute stages of takotsubo syndrome: Results from the Stockholm myocardial infarction with normal coronaries 2 study

AIMS

It is well-accepted that takotsubo syndrome (TS) is characterized by a massive surge of plasma catecholamines despite lack of solid evidence. The objective of this study was to examine the hypothesis of a massive catecholamine elevation in TS by studying plasma-free catecholamine metabolites in patients participating in the Stockholm myocardial infarction (MI) with normal coronaries 2 (SMINC-2) study where TS constituted more than one third of the patients.

METHODS AND RESULTS

The patients included in the SMINC-2 study were classified, according to cardiac magnetic resonance (CMR) imaging findings (148 patients), which was performed at a median of 3 days after hospital admission. Plasma-free catecholamine metabolites; metanephrine, normetanephrine, and methoxy-tyramine were measured on day 2-4 after admission. Catecholamine metabolite levels were available in 125 patients. One hundred and ten (88%) of the 125 patients included in SMINC-2 study, and 38 (86.4%) of the 44 patients with TS had completely normal plasma metanephrine and normetanephrine levels. All patients had normal plasma methoxy-tyramine levels. Fourteen (11.2%) of the 125 patients included in SMINC-2 study, and 5 (11.6%) of the 43 patients with TS had mild elevations (approximately 1.2 times the upper normal limits) of either plasma metanephrine or normetanephrine. One patient with pheochromocytoma-triggered TS had marked elevation of plasma metanephrine and mild elevation of plasma normetanephrine. There were no significant differences between the number or degree of catecholamine metabolite elevations between the different groups of patients with CMR imaging diagnosis included in SMINC-2 study.

CONCLUSION

There was no evidence of massive catecholamine elevations in the acute and subacute stages of TS apart from one patient with pheochromocytoma-induced TS. Most of the TS patients had normal catecholamine metabolites indicating that blood-borne catecholamines do not play a direct role in the pathogenesis of TS.

The Brain-Heart Link: A Case Report of a Critically Located Multiple Sclerosis Lesion in the Brainstem Leading to Recurrent Takotsubo Syndrome

Various central nervous system (CNS) diseases, including neurovascular and neuroinflammatory diseases, can lead to stress cardiomyopathy, also known as Takotsubo syndrome (TTS). We present a case of a 69-year-old woman with cardiovascular comorbidities, suffering from repeated episodes of TTS and respiratory failure due to a critical lesion in the brainstem, leading to a diagnosis of multiple sclerosis (MS). Despite aggressive treatment, intractable and recurrent symptoms in our patient occurred. Repeated bouts of autonomic dysfunction and respiratory failure ultimately led to installment of palliative care and the patient passing away. TTS should raise suspicion for underlying neurological diseases. Thorough questioning of previous neurological symptoms and extensive neurological workup is warranted. MS should be considered as a trigger of TTS also in elderly patients with cardiovascular risk factors.

Takotsubo Cardiomyopathy: Current Treatment

Management of takotsubo syndrome (TTS) is currently empirical and supportive, via extrapolation of therapeutic principles worked out for other cardiovascular pathologies. Although it has been emphasized that such non-specific therapies for TTS are consequent to its still elusive pathophysiology, one wonders whether it does not necessarily follow that the absence of knowledge of TTS' pathophysiological underpinnings should prevent us for searching, designing, or even finding, therapies efficacious for its management. Additionally, it is conceivable that therapy for TTS may be in response to pathophysiological/pathoanatomic/pathohistological consequences (e.g., "myocardial stunning/reperfusion injury"), common to both TTS and coronary artery disease, or other cardiovascular disorders). The present review outlines the whole range of management principles of TTS during its acute phase and at follow-up, including considerations pertaining to the recurrence of TTS, and commences with the idea that occasionally management of TTS should consist of mere observation along the "first do no harm" principle, while self-healing is under way. Finally, some new therapeutic hypotheses (i.e., large doses of insulin infusions in association with the employment of intravenous short- and ultrashort-acting β-blockers) are being entertained, based on previous extensive animal work and limited application in patients with neurogenic cardiomyopathy and TTS.

Insulin and takotsubo syndrome: plausible pathophysiologic, diagnostic, prognostic, and therapeutic roles

The pathophysiology of takotsubo syndrome (TTS) is elusive. Heightened adrenergic surge via the sympathetic nervous system (mainly by norepinephrine secretion) and/or elevated blood-borne catecholamines (mainly epinephrine, secreted by the adrenals) probably mediate TTS. Patients with TTS have a low prevalence of diabetes mellitus (DM), and it has been postulated that DM, via its associated neuropathy, prevents the emergence of TTS. Insulin, in animal experiments, has been shown to greatly attenuate the effects of NE on the cardiomyocytes; also, insulin in a limited clinical experience, has been found to improve heart function in patients with neurogenic stress-cardiomyopathy and TTS. Accordingly, it is postulated that high levels of insulin encountered in patients with type 2 DM are at the roots of the protective effect of DM for the emergence of TTS. Thus, a role of insulin in the pathophysiology, diagnosis, prognosis, and therapy of TTS appears to be plausible, and needs exploration.

Current Knowledge and Future Challenges in Takotsubo Syndrome: Part 1-Pathophysiology and Diagnosis

First recognized in 1990, takotsubo syndrome (TTS) constitutes an acute cardiac condition that mimics acute myocardial infarction commonly in the absence of obstructive coronary artery disease; it is characterized by temporary left ventricular dysfunction, regularly in a circumferential apical, midventricular, or basal distribution. Considering its acute clinical presentation, coronary angiography with left ventriculography constitutes the gold standard diagnostic tool to exclude or confirm TTS. Frequently, TTS is related to severe emotional or physical stress and a subsequent increased adrenergic stimulation affecting cardiac function. Beyond clinical presentation, epidemiology, and novel diagnostic biomarkers, this review draws attention to potential pathophysiological mechanisms for the observed reversible myocardial dysfunction such as sympathetic overdrive-mediated multi-vessel epicardial spasms, microvascular dysfunction, the direct toxicity of catecholamines, lipotoxicity, and inflammation. Considering the long-term prognosis, further experimental and clinical research is indispensable to elucidate further pathophysiological mechanisms underlying TTS before randomized control trials with evidence-based therapeutic management can be performed.