Transthoracic Doppler ultrasound coronary flow reserve evaluation: preliminary insights into pathophysiology of Takotsubo cardiomyopathy

Takotsubo Syndrome: Clinical Manifestations, Etiology and Pathogenesis

The purpose of the review is the analysis of clinical and experimental data on the etiology and pathogenesis of takotsubo syndrome (TS). TS is characterized by contractile dysfunction, which usually affects the apical region of the heart without obstruction of coronary artery, moderate increase in myocardial necrosis markers, prolonged QTc interval (in 50% of patients), sometimes elevation of ST segment (in 19% of patients), increase N-Terminal Pro-B-Type Natriuretic Peptide level, microvascular dysfunction, sometimes spasm of the epicardial coronary arteries (in 10% of patients), myocardial edema, and life-threatening ventricular arrhythmias (in 11% of patients). Stress cardiomyopathy is a rare disease, it is observed in 0.6 - 2.5% of patients with acute coronary syndrome. The occurrence of takotsubo syndrome is 9 times higher in women, who are aged 60-70 years old, than in men. The hospital mortality among patients with TS corresponds to 3.5% - 12%. Physical or emotional stress do not precede disease in all patients with TS. Most of patients with TS have neurological or mental illnesses. The level of catecholamines is increased in patients with TS, therefore, the occurrence of TS is associated with excessive activation of the adrenergic system. The negative inotropic effect of catecholamines is associated with the activation of β2 adrenergic receptors. An important role of the adrenergic system in the pathogenesis of TS is confirmed by studies which were performed using 125I-metaiodobenzylguanidine (125I -MIBG). TS causes edema and inflammation of the myocardium. The inflammatory response in TS is systemic. TS causes impaired coronary microcirculation and reduces coronary reserve. There is a reason to believe that an increase in blood viscosity may play an important role in the pathogenesis of microcirculatory dysfunction in patients with TS. Epicardial coronary artery spasm is not obligatory for the occurrence of TS. Cortisol, endothelin-1 and microRNAs are challengers for the role of TS triggers. A decrease in estrogen levels is a factor contributing to the onset of TS. The central nervous system appears to play an important role in the pathogenesis of TS.

[Clinical Manifestation of Stressful Cardiomyopathy (Takotsubo Syndrome) and the Problem of Differential Diagnosis with Acute Myocardial Infarction]

The presented data show that tacotsubo syndrome (TS) is characterized by the absence of coronary artery obstruction, cardiac contractile dysfunction, apical ballooning, and heart failure, and in some patients, ST-segment elevation and prolongation of the QTc interval. Every tenth patient with TS develops ventricular arrhythmias. Most of TS patients have elevated markers of necrosis (troponin I, troponin Т, and creatine kinase МВ (CK-МВ), which are considerably lower than in patients with acute myocardial infarction (AMI) with ST-segment elevation. The level of N-terminal pro-B-type natriuretic peptide (NT-proBNP), in contrast, is considerably higher in patients with TS than with AMI. Differential diagnosis of TS and AMI should be based on a multifaceted approach using coronary angiography, echocardiography, analysis of ECG, magnetic resonance imaging, single-photon emission computed tomography, and measurement of troponins, CK-MB, and NT-proBNP.

Role of Coronary Microvascular Dysfunction in Takotsubo Cardiomyopathy

Takotsubo cardiomyopathy (TTC) is a relatively frequent acute cardiac condition, but its pathogenesis has not been established as yet. Since the first descriptions of TTC, microvascular dysfunction has been advocated as a possible pathophysiological mechanism underlying the left ventricular wall motion abnormalities that characterize the syndrome. Several noninvasive and invasive methods have confirmed the involvement of coronary microvascular abnormalities in the pathogenesis of TTC, but whether microvascular dysfunction is the primary cause or a secondary phenomenon is still debated. The greater prevalence of TTC among postmenopausal women, along with the relationship identified between physical and emotional triggers and other "neuro-cardiac" mechanisms, suggest that increased microvascular reactivity, possibly sympathetically mediated, may play a pathogenic role in susceptible individuals. This review critically evaluates the possible role of microvascular dysfunction in the development of TTC.

Coronary flow reserve during dobutamine stress in Takotsubo stress cardiomyopathy

OBJECTIVES

Takotsubo stress cardiomyopathy (TSC) is an increasingly recognised and diagnosed disease, although the underlying pathophysiology is still unknown. Our aim was to investigate the effect of the catecholamine dobutamine on coronary flow reserve (CFR) measured non-invasively in patients with TSC and controls. Our hypothesis was that dobutamine stress can induce microvascular dysfunction in patients with a previous episode of TSC.

SETTING

This is a case-control study and a substudy of the Stockholm Myocardial Infarction with Normal Coronaries (SMINC) study. Elective dobutamine investigations were performed focusing on non-invasive measurements of CFR. The investigations were performed more than 6 months after the acute event.

PARTICIPANTS

22 patients with a previous episode of TSC and 22 sex-matched and age-matched controls were recruited from the SMINC study. All patients with TSC had a previous normal cardiovascular MR investigation.

RESULTS

CFR at low-dose dobutamine was significantly lower in the TSC group compared with controls, 1.51 and 1.72, respectively (p=0.017). At high-dose dobutamine, CFR was 1.95 and 2.21 in the TSC group and controls, respectively (p=0.098).

CONCLUSIONS

We could not confirm that the catecholamine dobutamine induced microvascular dysfunction in patients with TSC. However, we found a small but significant difference in CFR at low-dose dobutamine, which implies that the role of microvascular function in TSC needs to be further explored.

Brachial artery flow-mediated dilation in patients with Tako-tsubo cardiomyopathy

BACKGROUND

Tako-Tsubo cardiomyopathy (TTC) is a heart syndrome associated with transient myocardial contractile dysfunction. The pathogenesis of TTC remains unclear. The purpose of this study was to investigate brachial artery flow-mediated dilation (FMD) in patients with TTC.

METHODS

The results of FMD tests of 4 women with TTC were compared with the results from 18 women with ST-elevation acute myocardial infarction (STEMI) and from 26 healthy female volunteers. FMD tests in all patients were performed within 24 hours of admission and again at 1-3 weeks as a follow-up.

RESULTS

The FMD levels were significantly lower at the acute phase in patients with TTC than in patients with STEMI and in healthy volunteers (P <.01). After 1-3 weeks, the FMD test results of patients with TTC had greatly increased, and no significant differences were found between these results and the results from patients with STEMI (P >.05). Also, there were no significant differences in the FMD test results between the group of patients with TTC and the group of healthy volunteers (P >.05).

CONCLUSIONS

There is a pronounced and reversible endothelial dysfunction in patients with TTC, which can impair myocardial perfusion.

Neurogenic stunned myocardium and takotsubo cardiomyopathy are the same syndrome: a pooled analysis

Neurogenic stunned myocardium (NSM) and Takotsubo cardiomyopathy (TCM) are two syndromes that coexist in the medical literature. They share many common features. We hypothesized that they, in fact, represent the same syndrome. We collected and analyzed case reports of transient left ventricular (LV) dysfunction in neurologic conditions. Cases were compared based on the diagnosis and then based on the pattern of wall motion abnormality. Of 112 cases, 61 were diagnosed as TCM and 37 as NSM, and in 14 cases, the authors used both terms. Overall, the patients with NSM were younger, and the severity of LV systolic dysfunction and timing of recovery was similar, as well as the prevalence of cardiac enzyme elevation. Pulmonary edema on presentation was more prevalent in patients with NSM while chest pain and ST-segment elevation was more common in patients with TCM. While only regional, predominantly apical, wall motion abnormality was described in TCM, some patients in the NSM group had global LV dysfunction. NSM and TCM likely share the same mechanism and pathologic substrate. Their natural course is almost identical. They both likely represent the same syndrome of stress-induced cardiomyopathy. Current definition of stress-induced cardiomyopathy includes only regional wall motion abnormalities. It should be expanded to include all varieties of wall motion abnormalities including global hypokinesis.

Abnormal coronary reserve and left ventricular wall motion during cold pressor test in patients with previous left ventricular ballooning syndrome

AIMS

To investigate whether and how cold pressor test (CPT) could affect myocardial perfusion and left ventricular (LV) function in patients with previous LV ballooning syndrome (LVBS).

METHODS AND RESULTS

Cold pressor test (3 min hand immersion in ice-water) was performed in 17 women with previous LVBS and in 7 age- and risk factor-matched women with chest pain and normal coronary arteries. At baseline and peak CPT, global and regional LV function, and myocardial perfusion were quantitatively assessed by real-time three-dimensional echocardiography (RT3DE) and myocardial contrast (SonoVue, Bracco) 2D echocardiography (MCE), respectively (Philips iE33 machine, X3-1 and S5-1 probes). Data were analysed off-line (QLab 6.0 software). Peripheral venous catecholamines were assayed by high performance liquid chromatography with electrochemical detection. Cold pressor test induced similar haemodynamic changes and catecholamine increase in controls and LVBS patients. Left ventricular ejection fraction decreased and transient new mid-ventricular and apical motion abnormalities developed in LVBS patients only (quantitative RT3D analysis), without corresponding perfusion defects (MCE). At peak CPT, coronary blood flow and velocity increased (quantitative MCE analysis) in control subjects only.

CONCLUSION

Cold pressor test induced LV wall motion abnormalities unmatched to regional coronary flow reduction in LVBS patients only. The reduced coronary reserve in response to CPT suggests microvascular dysfunction in LVBS patients.