'Acute micro-coronary syndrome': detailed coronary physiology in a patient with Takotsubo cardiomyopathy

Stress-induced cardiomyopathy by dobutamine stress echocardiography during recovery stage - A rare presentation

Stress-induced cardiomyopathy is a condition of acute myocardial suppression following an abrupt release of endogenous catecholamines after emotional or physical stress. The exact mechanism is unknown but there are reports of a similar clinical presentation after injection of exogenous catecholamines such as beta agonists. We report a rare type of stress-induced cardiomyopathy following injection of dobutamine during a diagnostic stress echocardiography.

Learning objective

Stress-induced cardiomyopathy by dobutamine stress echocardiography is a rare entity and it should be included as a differential cause of regional wall motion abnormality during stress echocardiography. Physicians must be aware of this since treatment and follow up of these patients may differ from those for other patients and it may cause heart failure.

Takotsubo Syndrome and Coronary Artery Disease: Which Came First-The Chicken or the Egg?

Takotsubo syndrome (TTS) is a clinical condition characterized by temporary regional wall motion anomalies and dysfunction that extend beyond a single epicardial vascular distribution. Various pathophysiological mechanisms, including inflammation, microvascular dysfunction, direct catecholamine toxicity, metabolic changes, sympathetic overdrive-mediated multi-vessel epicardial spasms, and transitory ischemia may cause the observed reversible myocardial stunning. Despite the fact that TTS usually has an acute coronary syndrome-like pattern of presentation, the absence of culprit atherosclerotic coronary artery disease is often reported at coronary angiography. However, the idea that coronary artery disease (CAD) and TTS conditions are mutually exclusive has been cast into doubt by numerous recent studies suggesting that CAD may coexist in many TTS patients, with significant clinical and prognostic repercussions. Whether the relationship between CAD and TTS is a mere coincidence or a bidirectional cause-and-effect is still up for debate, and misdiagnosis of the two disorders could lead to improper patient treatment with unfavourable outcomes. Therefore, this review seeks to provide a profound understanding of the relationship between CAD and TTS by analyzing potential common underlying pathways, addressing challenges in differential diagnosis, and discussing medical and procedural techniques to treat these conditions appropriately.

Microvascular function and inflammatory activation in Takotsubo cardiomyopathy

AIMS

The aim of this study was to determine microvascular function in the acute phase of Takotsubo syndrome (TTS) and to identify inflammatory mediators that could reflect TTS-induced pathology.

METHODS AND RESULTS

The study included 20 females [median age 65 years; interquarile range (IQR) = 58-70 years] with TTS according to the Mayo diagnostic criteria. During heart catheterization, we determined the index of microvascular resistance (IMR) and drew blood samples almost simultaneously from the aorta and coronary sinus. Cardiac magnetic resonance imaging (MRI) was done in the acute phase. We present descriptive coronary physiology and cardiac MRI data and compare inflammatory biomarkers between samples from the aorta, coronary sinus, and venous samples after 3 months using the Wilcoxon signed-rank test. For comparison, we also analysed the actual biomarkers in venous blood from 15 healthy female controls. A supplementary analysis explored Spearman's rank correlation between the inflammatory biomarkers, IMR, MRI data, and cardiac biomarkers. The median IMR was 16.5 mmHg·s (IQR = 10.5-28.2 mmHg·s), which was only slightly higher than that in the reference populations. Seven (35%) of the study subjects had IMR > 25 mmHg·s, suggesting a microvascular dysfunction. IMR was not affected by time from symptom onset. According to MRI, the apical region of the left ventricle was affected in 65% of the subjects. The median ejection fraction was 41% (IQR = 31-48%). Biomarker analyses revealed elevation of markers for extracellular matrix remodelling and fibrosis, inflammation, immune activation, and upstream inflammation as compared with healthy controls. Only the levels of interleukin (IL)-1 receptor antagonist and soluble T-cell immunoglobulin mucin domain-3 (sTIM-3) were higher in the coronary sinus than in the aorta. No variable was significantly correlated with IMR. The IL-6 level in the aorta was inversely correlated with the left ventricular ejection fraction. Growth differentiation factor-15, osteoprotegerin, and von Willebrand factor levels in both aorta and coronary sinus were positively correlated with N-terminal-pro-brain-natriuretic peptide, while the correlations of IL-6 and sTIM-3 with N-terminal-pro-brain-natriuretic peptide were restricted to the aorta and coronary sinus, respectively. While most of the markers were within normal limits after 3 months, matrix metalloproteinase-9 increased during follow-up to reach levels higher than those in the healthy controls.

CONCLUSION

The median IMR was only slightly elevated in this study, but about one-third of the patients had values indicating microvascular dysfunction. The present study supports the involvement of several inflammatory pathways in TTS, including monocyte/macrophage activation, with sTIM-3 as a potential novel marker.

Serial changes of myocardial perfusion imaging in takotsubo and reverse takotsubo cardiomyopathy

BACKGROUND

Takotsubo cardiomyopathy (TTC) shows reversible hypokinesis in the left ventricular (LV) apical-half segment and hyperkinesis in the LV basal-half segment. However, the precise pathophysiological mechanism of TTC is unclear. Therefore, this study sought to clarify the nuclear characteristics, degree of myocardial damage, and serial change of TTC and rTTC using myocardial perfusion imaging.

METHODS

We performed myocardial perfusion scintigraphy in 28 patients (TTC: 20, rTTC: 8) using Tc-99m sestamibi and assessed minimum percentage uptake (min-%-uptake), extent score (ES) and summed rest score (SRS) at acute and chronic phases.

RESULTS

Min-%-uptake improved from the acute to the chronic phase (TTC: 54 [48-59]% vs 87 [81-90]%, P  < 0.01; rTTC: 60 [55-64]% vs 77 [71-79]%, P < 0.01), as did the ES (TTC: 32 [26-41]% vs 0.0 [0.0-6.0]%, P < 0.01; rTTC: 16 [12-34]% vs 0.0 [0.0-0.0]%, P = 0.02) and SRS (TTC: 4.5 [3.9-5.3] vs 0.0 [0.0-0.2], P < 0.01; rTTC: 3.6 [3.3-3.8] vs 0.0 [0.0-0.0], P = 0.01).

CONCLUSION

Tc-99m sestamibi uptake was reduced in hypokinetic regions in the acute phase and improved in the chronic phase. TTC and rTTC may involve a reversible disorder of the myocardial cell membrane, mitochondria, and microcirculation.

Coronary microvascular dysfunction in Takotsubo syndrome: cause or consequence

Takotsubo syndrome (TS) is an acute cardiac disease entity, characterized by a transient myocardial stunning in a distinctive predominantly regional circumferential pattern. One of the discussed pathological mechanisms of TS is coronary ischemia including coronary microvascular dysfunction (CMVD). Many studies have revealed invasive or non-invasive signs of CMVD in patients with TS, and therefore some investigators believe that CMVD is the primary cause of TS. Nevertheless, other studies have not shown any sign of CMVD. In addition, those studies, which have shown signs of CMVD, do not reveal such signs in all the three coronary vessel distribution; some of the patients show signs of CMVD in two or only one coronary artery territory. Moreover, signs of CMVD in TS are more prevalent and more pronounced in the left anterior descending artery (LAD) distribution. The CMVD in TS is reversible in a pattern parallel to the improvement of myocardial wall motion abnormality. In this review, substantial evidences challenging CMVD as the primary cause of TS and supporting the concept that CMVD is a secondary or epiphenomenon in TS are provided. Furthermore, convincing explanation is given for the causes of the more prevalent and the more pronounced signs of CMVD observed in the LAD distribution.