Coincidence of coronary artery disease and Tako-Tsubo cardiomyopathy

Update of Takotsubo cardiomyopathy: Present experience and outlook for the future

Takotsubo cardiomyopathy (TTS) has become a recognised clinical entity since the Japanese scientist Sato first described it in 1990.

Despite an increasing number of confirmed cases, especially during the COVID-19 pandemic, its pathophysiology remains incompletely understood, and decision-making differs in the diagnosis and treatment. In addition, it is not evident whether a significant increase in TTS is due to better understanding among practitioners and widespread access to coronary angiography, or if it is a reflection of an actual increase in incidence.

We analysed a series of international research studies from 1990 to 2021. Beyond epidemiology and clinical presentation, we evaluated and summarised fundamental knowledge about various predisposing factors, with particular attention to the iatrogenic impact of certain drugs, namely antidepressants, chemotherapy, and antiarrhythmics.

Furthermore, we highlighted the main pathophysiological theories to date. In addition, based on published studies and clinical cases, we investigated the role of numerous diagnostic approaches in the differential diagnosis of TTS and identified predictors of TTS complications, such as cardiogenic shock, ventricular fibrillation, and left ventricular thrombi. Accordingly, we sought to propose a diagnostic algorithm and further treatment management of TTS under the presence of possible complications to help practitioners make more informed decisions, as the initial presentation continues to pose a challenge due to its close similarity to acute coronary syndrome with ST-elevation.

In conclusion, this article examines Takotsubo cardiomyopathy from different perspectives and, along with future systematic reviews and meta-analyses, can be of particular interest to practising cardiologists and researchers in developing clinical guidelines.

Optical Coherence Tomography to Evaluate Plaque Burden and Morphology in Patients With Takotsubo Syndrome

BACKGROUND

Disrupted atherosclerotic plaques in the left anterior descending coronary artery are discussed controversially as a potential pathophysiological mechanism in Takotsubo syndrome (TTS). Therefore, the aim of the present study was to assess plaque burden and morphology by using optical coherence tomography in patients with TTS.

METHODS AND RESULTS

A total of 23 consecutive TTS patients were included in this single-center study and underwent optical coherence tomography imaging of the left main coronary artery and the left anterior descending coronary artery at acute presentation. All patients fulfilled the established diagnostic criteria for TTS and the diagnosis was confirmed with a multimodality imaging approach including cardiac magnetic resonance in 16 patients (69.6%). Atherosclerotic plaques located in the left anterior descending coronary artery or both the left anterior descending coronary artery and the left main coronary artery were detected in 16 TTS patients (69.6%), with 6 patients exhibiting multiple plaque types. In addition to the predominant fibrocalcific (52.2%) and lipid-rich plaques (30.4%), thin-cap fibroatheromas were also found in 6 patients (26.1%). However, ruptured plaques or intracoronary thrombi were not observed. Vessel stenosis >50% was found in 3 patients (13.0%) by analyzing cross-sectional areas. Clinical characteristics and cardiac magnetic resonance findings did not differ significantly between TTS patients with and without atherosclerotic plaques.

CONCLUSIONS

Using optical coherence tomography, the present study revealed a high prevalence of atherosclerotic plaques in patients with TTS, including a considerable number of highly vulnerable thin-cap fibroatheromas. However, ruptured plaques or intracoronary thrombi were not observed and are therefore most likely not the underlying mechanism of TTS.

[Tako-tsubo syndrome: analysis of a series of 60 cases]

BACKGROUND AND OBJECTIVE

The Tako-tsubo syndrome (TS) is a reversible acute cardiomyopathy simulating an infarction. We analyzed 60 patients admitted with TS in our center.

PATIENTS AND METHOD

A percentage of 73.3 were women (mean age: 70.6 ± 11.8 years); 83.3% had some cardiovascular risk factor, 25% had an anxiety-depressive disorder and in 58.3% a precipitating factor was identified, emotional stress being the most frequent. A percentage of 15.3 showed complete left bundle branch block (LBBB). In 23.3% of patients, contractile abnormalities respected the apex (mid ventricular or diaphragmatic types).

RESULTS

The anterior descending artery showed no significant lesions in 35% of patients and in 68.3% it had a diaphragmatic segment. Forty percent of patients developed heart failure (HF) and 18.3% cardiogenic shock (CS). The overall in-hospital mortality was 3.3%, while it was 8.3% among those patients who developed HF. The incidence of CS was higher among patients with LBBB (44.4 vs. 13.7%, P=.05) and males (43.8 vs. 9.1%, P=.005).

CONCLUSIONS

Although in-hospital mortality in patients admitted due to TS is low, a significant percentage of these patients develop HF with a high mortality in this subgroup. Males and patients with LBBB had higher in-hospital morbidity.

[Patient care in the acute phase of stress induced cardiomyopathy (Tako-Tsubo cardiomyopathy)--and thereafter?]

The prognosis of patients presenting with Tako-Tsubo cardiomyopathy (TTC) is generally considered to be favorable. However, in the acute phase of the disorder complications are not infrequent and, therefore, continuous monitoring and consistent therapy in an intensive care unit is essential. Typical complications in patients with TTC are cardiogenic shock, obstruction of the left ventricular outflow tract (LVOT), occasionally accompanied by acute mitral regurgitation, arrhythmias, predominantly torsade de pointes tachycardias due to QT prolongation, left ventricular (LV) thrombus formation with or without consecutive thromboembolic events, and LV rupture. After confirmation of TTC by coronary angiography, repeat echocardiography should be performed. A standardized therapy for patients with TTC has so far not been established. Recommendations for the acute phase include the administration of anxiolytic agents for patients who present with preceding emotional stress, consistent therapy of physical stressors (such as pain or asthma) and avoidance of catecholamine therapy. Shock due to LVOT obstruction is treated by administration of volume and β-blockers. With respect to the occurrence of torsade de pointes tachycardias, drugs which might cause QT prolongation should not be given. The notable incidence of LV thrombus formation justifies therapeutic anticoagulation. Systematic studies and treatment recommendations for the prophylaxis of recurrent TTC do not exist. The recently reported association between TTC and malignant disorders should prompt tumor screening and subsequent preventive medical checkups in patients affected by TTC.

Novel aspects and new roles for the serine protease plasmin

The serine protease plasmin is distributed throughout the human body in the form of the zymogen plasminogen. The plasminogen activation system is mostly recognized for its fibrinolytic activity but is also upregulated in chronic inflammatory diseases, including atherosclerosis and arthritis. Plasmin can bind to a variety of cells, including monocytes, through low-affinity binding sites and triggers aggregation of neutrophils, platelet degranulation and arachidonate release from endothelial cells. In monocytes, plasmin elicits full-scale proinflammatory activation, including lipid mediator release, chemotaxis and cytokine expression, as well as induction of other proinflammatory genes. The effects of plasmin are specific, require the active catalytic center and can be antagonized by lysine analogues, implying binding of the plasmin molecule to the cell membrane through its lysine binding sites. In view of the upregulation of the fibrinolytic genes in chronic inflammatory diseases, cell activation by plasmin is likely to play a major pathophysiological role, a view that is further supported by data from transgenic mice.

Targeting of the Akt/PKB kinase to the actin skeleton

Serine/threonine kinase Akt/PKB intracellular distribution undergoes rapid changes in response to agonists such as Platelet-derived growth factor (PDGF) or Insulin-like growth factor (IGF). The concept has recently emerged that Akt subcellular movements are facilitated by interaction with nonsubstrate ligands. Here we show that Akt is bound to the actin skeleton in in situ cytoskeletal matrix preparations from PDGF-treated Saos2 cells, suggesting an interaction between the two proteins. Indeed, by immunoprecipitation and subcellular fractioning, we demonstrate that endogenous Akt and actin physically interact. Using recombinant proteins in in vitro binding and overlay assays, we further demonstrate that Akt interacts with actin directly. Expression of Akt mutants strongly indicates that the N-terminal PH domain of Akt mediates this interaction. More important, we show that the partition between actin bound and unbound Akt is not constant, but is modulated by growth factor stimulation. In fact, PDGF treatment of serum-starved cells triggers an increase in the amount of Akt associated with the actin skeleton, concomitant with an increase in Akt phosphorylation. Conversely, expression of an Akt mutant in which both Ser473 and Thr308 have been mutated to alanine completely abrogates PDGF-induced binding. The small GTPases Rac1 and Cdc42 seem to facilitate actin binding, possibly increasing Akt phosphorylation.