Metoprolol, propranolol, carvedilol, or labetalol for patients with Takotsubo syndrome?

Orexin/hypocretin system dysfunction in patients with Takotsubo syndrome: A novel pathophysiological explanation

Takotsubo syndrome (TTS) is an acute heart failure syndrome. Emotional or physical stressors are believed to precipitate TTS, while the pathophysiological mechanism is not yet completely understood. During the coronavirus disease (COVID-19) pandemic, an increased incidence of TTS has been reported in some countries; however, the precise pathophysiological mechanism for developing TTS with acute COVID-19 infection is unknown. Nevertheless, observing the symptoms of COVID-19 might lead to new perspectives in understanding TTS pathophysiology, as some of the symptoms of the COVID-19 infection could be assessed in the context of an orexin/hypocretin-system dysfunction. Orexin/hypocretin is a cardiorespiratory neuromodulator that acts on two orexin receptors widely distributed in the brain and peripheral tissues. In COVID-19 patients, autoantibodies against one of these orexin receptors have been reported. Orexin-system dysfunction affects a variety of systems in an organism. Here, we review the influence of orexin-system dysfunction on the cardiovascular system to propose its connection with TTS. We propose that orexin-system dysfunction is a potential novel explanation for the pathophysiology of TTS due to direct or indirect dynamics of orexin signaling, which could influence cardiac contractility. This is in line with the conceptualization of TTS as a cardiovascular syndrome rather than merely a cardiac abnormality or cardiomyopathy. To the best of our knowledge, this is the first publication to present a plausible connection between TTS and orexin-system dysfunction. We hope that this novel hypothesis will inspire comprehensive studies regarding orexin's role in TTS pathophysiology. Furthermore, confirmation of this plausible pathophysiological mechanism could contribute to the development of orexin-based therapeutics in the treatment and prevention of TTS.

Pretreatment with Betablockers, a Potential Predictor of Adverse Cardiovascular Events in Takotsubo Syndrome

Introduction: Treatment with betablockers is controversial in Takotsubo syndrome (TTS); however, many physicians intuitively initiate or continue betablocker therapy in these patients. The effect of preadmission betablocker use on adverse cardiovascular events has not been studied in the literature. Methods: To investigate this issue, we evaluated clinical complications, defined by the endpoint of occurrence of hemodynamically relevant arrythmia, cardiac decompensation, and all-cause adverse cardiac events, during hospitalization, in 56 patients hospitalized for TTS between April 2017 and July 2021. We compared the risk of adverse cardiovascular events between patients with preadmission betablocker therapy and those without preadmission betablocker therapy. Pretreatment betablocker therapy was defined as daily betablocker intake for more than a week including day of admission. Results: TTS patients taking preadmission betablockers had a significantly increased risk of all-cause complications relative to patients without betablockers in preadmission medication ((52.0% vs. 19.4%, p = 0.010; OR 4.5 (95% Cl 1.38–14.80)). Furthermore, TTS patients already taking betablockers on admission showed a statistically significant increased risk of cardiac decompensation when compared to patients without pretreatment with betablockers (p = 0.013). There were no significant differences in patient characteristics in patients who were taking beta blockers as an adjunct therapy prior to admission for TTS relative to those who were not. There is however an increase in comorbidities, hypertension, and atrial fibrillation, in past medical history in patients taking a preadmission betablocker. The difference is related to therapeutic applications for beta blockers and was not significant based on endpoints of our study. Conclusions: Preadmission betablocker treatment was associated with a 4.5 times higher risk of adverse cardiac events. This increased risk of all-cause complications and of cardiac decompensation within the acute phase of TTS is presumably due to the negative inotropic effects of betablockers and upregulation of β-adrenergic receptors in patients with chronic betablocker therapy.

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.

Indications of beta-adrenoceptor blockers in Takotsubo syndrome and theoretical reasons to prefer agents with vasodilating activity

Takotsubo syndrome (TTS) is estimated to account for 1-3% of all patients presenting with suspected ST-segment elevation myocardial infarction. A sudden surge in sympathetic nervous system is considered the cause of TTS. Nonetheless, no specific recommendations have been provided regarding β-blocking therapy. Apart from specific contra-indications (severe LV dysfunction, hypotension, bradycardia and corrected QT interval >500 ms), treatment with a β-blocker seems reasonable until full recovery of LV ejection fraction, though evidence is limited to a few animal studies, case reports or observational studies. In this review, we will reappraise the rationale for β-blocker therapy in TTS and speculate on the pathophysiologic basis for preferring non-selective agents with vasodilating activity over β₁-selective drugs.

Reversible exercise-induced left ventricular dysfunction in symptomatic patients with previous Takotsubo syndrome: insights from stress echocardiography

AIMS

Takotsubo syndrome (TTS) is usually associated with rapid and spontaneous recovery of left ventricular (LV) function. However, a proportion of patients may have persistent symptoms. This study aimed to determine the haemodynamic and LV contractile responses to exercise in these patients.

METHODS AND RESULTS

Thirty symptomatic TTS patients referred for exercise echocardiography, a median of 15 months following the index TTS episode, were matched with 30 controls with normal exercise echocardiography. Beta-blockers were withheld prior to the test. LV volumes, ejection fraction (EF) and wall motion score index (WMSI), were measured at rest and stress. The TTS cohort were Caucasian women with mean age of 64.6 ± 7.4 years and similar coronary risk factor profile and EF to controls. Resting systolic blood pressure (SBP), LV end-diastolic volume, wall stress, and right ventricular fractional area change were higher in TTS patients compared with controls. Stress echo data showed similar exercise time, peak heart rate, and peak SBP in TTS patients vs. controls, but TTS patients had higher LV volumes, lower exercise LVEF (70 ± 10% vs. 78 ± 7%; P = 0.001), ΔLVEF (4 ± 8% vs. 12 ± 5%; P < 0.001), and WMSI (1.4 ± 0.4 vs. 1 ± 0; P < 0.001) compared with controls. Twenty TTS patients had clear exercise-induced wall motion abnormalities, mainly involving the apex or more globally, with a mean ΔLVEF of 1% compared with 12% in controls. Among the other 10 TTS patients, the ΔLVEF was 10%.

CONCLUSION

Symptomatic patients with previous TTS have a blunted contractile response to exercise. The therapeutic and prognostic implications of these findings need further investigation.