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

An Opportune Time to Consider Glucose-Insulin-Potassium Therapy for Takotsubo Syndrome

This viewpoint takes the position that the management of takotsubo syndrome (TTS) should not wait the elucidation of the pathophysiology of this mysterious malady but should move along the direction currently implemented for acute coronary syndromes (ACS). Accordingly, and since there is a current rekindled interest in the salutary effect of glucose-insulin-potassium (GIK) for the management of acute myocardial infarction, and in general of the broad domain of ACS, it is the opinion of this author that it is an opportune time for the same therapeutic principles, including GIK, applied for the broad domain of suspected ACS (in view of the prospective phase 3 IMMEDIATE-2 trial), to be considered for TTS.

Recurrent Takotsubo Syndrome Due to Hypoglycemic Attacks

Takotsubo syndrome (TTS) is a disorder with transient cardiac dysfunction triggered by stress. Rarely, hypoglycemia can also trigger TTS, but there are no case reports of repeated TTS due to hypoglycemia. We report the case of a 51-year-old Japanese woman who was brought to the emergency department with impaired consciousness and shock vitals. Blood tests revealed severe hypoglycemia. She also had an abnormal electrocardiogram with a QS pattern in the anterior thoracic guidance, which led to the diagnosis of TTS after repeated echocardiographic evaluation by a cardiologist. The diagnosis of hypoglycemic coma was made, and the patient was admitted to the intensive care unit (ICU). The patient had anorexia nervosa and had been suffering from a hypoglycemic coma due to anorexia for some time. The patient had a history of hypoglycemic coma about one year before and had been hospitalized in the ICU with TTS at that time. We report the world's first case of repeated TTS due to hypoglycemia. Since hypoglycemia is hemodynamically associated with increased heart rate and systolic blood pressure, TTS should be included in the differential diagnosis when shock vitals are repeated in patients with frequent hypoglycemia.

Metabolic remodeling in takotsubo syndrome

The heart requires a large and constant supply of energy that is mainly the result of an efficient metabolic machinery that converges on mitochondrial oxidative metabolism to maintain its continuous mechanical work. Perturbations in these metabolic processes may therefore affect energy generation and contractile function directly. Metabolism characteristics in takotsubo syndrome (TTS) reveals several metabolic alterations called metabolic remodeling, including the hyperactivity of sympathetic metabolism, derangements of substrate utilization, effector subcellular dysfunction and systemic metabolic disorders, ultimately contributing to the progression of the disease and the development of a persistent and long-term heart failure (HF) phenotype. In this review, we explore the current literature investigating the pathological metabolic alterations in TTS. Although the metabolic dysfunction in takotsubo hearts is initially recognized as a myocardial metabolic inflexibility, we suggest that the widespread alterations of systemic metabolism with complex interplay between the heart and peripheral tissues rather than just cardiometabolic disorders per se account for long-term maladaptive metabolic, functional and structural impairment under this condition. Therapeutic strategies with the recent evidence from small clinical and animal researches, especially for targeting substrate utilization and/or oxidative stress, might be promising tools to improve the outcome of patients with TTS beyond that achieved with traditional sympathetic inhibition and symptomatic therapies.

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.