Thomas Emil Christensen

Takotsubo cardiomyopathy, a two-stage recovery of left ventricular systolic and diastolic function as determined by cardiac magnetic resonance imaging

AIMS Takotsubo cardiomyopathy (TTC) is an entity mimicking acute myocardial infarction, characterized by transient severe systolic heart failure. Echocardiographic studies suggest that diastolic dysfunction is present in TTC at presentation; however, no reports exist regarding the time course of left ventricular (LV) recovery. This study describes the recovery of LV systolic and diastolic function in TTC. We hypothesized that, in TTC, there is diastolic dysfunction at admission, and that recovery is delayed compared with systolic function. METHODS AND RESULTS We enrolled (consecutively 2010-12) 16 patients (mean age 66, range 39-84 years) diagnosed with TTC and 20 healthy matched controls. We performed cardiac magnetic resonance imaging (CMR) at admission, pre-discharge, and 3-month follow-up. Diastolic function was assessed by LV peak filling rate (LVPFR) and left atrial (LA) emptying volumes. At admission, LV ejection fraction was low, increased at pre-discharge (37 ± 6 vs. 58 ± 6%, P < 0.001), and normalized at follow-up (to 65 ± 5%, P = 0.01). LVPFR did not increase during hospitalization (80 ± 3 vs. 89 ± 4 mL/s/m(2), P = 0.21), but was normalized at follow-up (to 206 ± 19, P < 0.001; controls, 214 ± 13, P = 0.23). During hospitalization, LA passive emptying volume remained low (6 ± 2 vs. 8 ± 3 mL/m(2), P = 0.05) and LA active emptying volume remained high (17 ± 3 vs. 16 ± 3 mL/m(2), P = 0.71), whereas LA conduit volume increased (7 ± 3 vs. 23 ± 4 mL/m(2), P < 0.001). T2-weighted imaging demonstrated non-coronary distributed apical oedema without contrast enhancement. CONCLUSION Patients with TTC undergo fast systolic recovery. However, at discharge, profound diastolic dysfunction is demonstrated by CMR. At follow-up, both LV systolic and diastolic function is normalized in patients with recovered TTC.

Is it possible to differentiate between Takotsubo cardiomyopathy and acute anterior ST-elevation myocardial infarction?

INTRODUCTION Several studies have investigated the ability of the twelve-lead electrocardiogram (ECG) to reliably distinguish Takotsubo cardiomyopathy (TC) from an acute anterior ST-segment elevation myocardial infarction (STEMI). In these studies, only ECG changes were required - ST-segment deviation and/or T-wave inversion - in TC whereas in acute anterior STEMI, ECGs had to meet STEMI criteria. In the majority of these studies, patients of both genders were used even though TC predominantly occurs in women. The aim of this study is to see whether TC can be distinguished from acute anterior STEMI in a predominantly female study population where all patients meet STEMI-criteria. METHODS Retrospective analysis of the ST-segment changes was done on the triage ECGs of 37 patients with TC (34 female) and was compared to the triage ECGs of 103 female patients with acute anterior STEMI. The latter group was divided into the following subgroups: 46 patients with proximal, 47 with mid and 10 with distal LAD occlusion. Three ST-segment based ECG features were investigated: (1) Existing criterion for differentiating anterior STEMI from TC: ST-segment depression >0.5mm in lead aVR+ST-segment elevation ≤1mm in lead V1, (2) frontal plane ST-vector and (3) mean amplitude of ST-segment deviation in each lead. RESULTS The existing ECG criterion was less accurate (76%) than in the original study (95%), with a large difference in sensitivity (26% vs. 91%). Only a frontal plane ST-vector of 60° could significantly distinguish TC from all acute anterior STEMI subgroups (p<0.01) with an overall diagnostic accuracy of 81%. The mean amplitude in inferior leads II and aVF was significantly higher for patients with TC compared to all patients with acute anterior STEMI (p<0.01 and p<0.05 respectively) and the mean amplitude in the precordial leads V1 and V2 was significantly lower compared to proximal and mid LAD occlusion (p<0.01). CONCLUSIONS Given the consequences of missing the diagnosis of an acute anterior STEMI the diagnostic accuracy of the ECG criteria investigated in this retrospective study were insufficient to reliably distinguish patients with TC from patients with an acute anterior STEMI. To definitely exclude the diagnosis of an acute anterior STEMI coronary angiography, which remains the gold standard, will need to be performed.

Multimodality Cardiac Imaging for the Assessment of Left Atrial Function and the Association With Atrial Arrhythmias

Several cardiac imaging modalities are able to visualize the left atrium (LA) and, therefore, allow for quantification of both structural and functional properties of this cardiac chamber. In echocardiography, only the maximal LA volume is included in the assessment of diastolic function at the current moment. Numerous studies, however, have shown that functional measures may be superior to the maximal LA volume in several aspects and to possess clinical value even in the absence of structural abnormalities. Such functional measures could prove particularly useful in the setting of predicting atrial fibrillation, which will be a point of focus in this review. Pivotal cardiac magnetic resonance imaging studies have revealed high correlation between LA fibrosis and risk of atrial fibrillation recurrence after catheter ablation, and subsequent multimodality imaging studies have uncovered an inverse relationship between LA reservoir function and degree of LA fibrosis. This has sparked an increased interest into the application of advanced imaging modalities, including both speckle tracking echocardiography and tissue tracking by cardiac magnetic resonance imaging. Even though increasing evidence has supported the use of functional measures and proven its superiority to the maximal LA volume, they have still not been adopted in clinical guidelines. The reason for this discrepancy may rely on the fact that there is little to no agreement on how to technically perform deformation analysis of the LA. Such technical considerations, limitations, and alternate imaging prospects will be addressed in this review.

Quantification of myocardial perfusion using cardiac magnetic resonance imaging correlates significantly to rubidium-82 positron emission tomography in patients with severe coronary artery disease: A preliminary study

INTRODUCTION Aim was to compare absolute myocardial perfusion using cardiac magnetic resonance imaging (CMRI) based on Tikhonovs procedure of deconvolution and rubidium-82 positron emission tomography (Rb-82 PET). MATERIALS AND METHODS Fourteen patients with coronary artery stenosis underwent rest and adenosine stress imaging by 1.5-Tesla MR Scanner and a mCT/PET 64-slice Scanner. CMRI were analyzed based on Tikhonovs procedure of deconvolution without specifying an explicit compartment model using our own software. PET images were analyzed using standard clinical software. CMRI and PET data was compared with Spearmans rho and Bland-Altman analysis. RESULTS CMRI results were strongly and significantly correlated with PET results for the absolute global myocardial perfusion differences (r=0.805, p=0.001) and for global myocardial perfusion reserve (MPR) (r=0.886, p<0.001). At vessel territorial level, CMRI results were also significantly correlated with absolute PET myocardial perfusion differences (r=0.737, p<0.001) and MPR (r=0.818, p<0.001). Each vessel territory had similar strong correlation for absolute myocardial perfusion differences (right coronary artery (RCA): r=0.787, p=0.001; left anterior descending artery (LAD): r=0.796, p=0.001; left circumflex artery (LCX): r=0.880, p<0.001) and for MPR (RCA: r=0.895, p<0.001; LAD: r=0.886, p<0.001; LCX: r=0.886, p<0.001). CONCLUSION On a global and vessel territorial basis, CMRI-measured absolute myocardial perfusion differences and MPR were strongly and significantly correlated with the Rb-82 PET findings.

Transthoracic Doppler echocardiography compared with positron emission tomography for assessment of coronary microvascular dysfunction: The iPOWER study

BACKGROUND Coronary microvascular function can be assessed by transthoracic Doppler echocardiography as a coronary flow velocity reserve (TTDE CFVR) and by positron emission tomography as a myocardial blood flow reserve (PET MBFR). PET MBFR is regarded the noninvasive reference standard for measuring coronary microvascular function but has limited availability. We compared TTDE CFVR with PET MBFR in women with angina pectoris and no obstructive coronary artery disease and assessed repeatability of TTDE CFVR. METHODS From a cohort of women with angina and no obstructive coronary artery stenosis at invasive coronary angiography, TTDE CFVR by dipyridamole induced stress and MBFR by rubidium-82 PET with adenosine was successfully measured in 107 subjects. Repeatability of TTDE CFVR was assessed in 10 symptomatic women and in 10 healthy individuals. RESULTS MBFR was systematically higher than CFVR. Median MBFR (interquartile range, IQR) was 2.68 (2.29-3.10) and CFVR (IQR) was 2.31 (1.89-2.72). Pearsons correlation coefficient was 0.36 (p<0.01). Limits of agreement (2·standard deviation) assessed by the Bland-Altman (confidence interval, CI) method was 1.49 (1.29;1.69) and unaffected by time-interval between examinations. Results were similar when adjusting for rate pressure product or focusing on perfusion of the left anterior descending artery region. Limits of agreement (CI) for repeated CFVR in 10 healthy individuals and in 10 women with angina was 0.44 (0.21;0.68) and 0.48 (0.22; 0.74), respectively. CONCLUSION CFVR had a good repeatability, but the agreement between CFVR and MBFR was modest. Divergence could be due to methodology differences; TTDE estimates flow velocities whereas PET estimates myocardial blood flow.

Basal hyperaemia is the primary abnormality of perfusion in Takotsubo cardiomyopathy: a quantitative cardiac perfusion positron emission tomography study

AIMS Takotsubo cardiomyopathy (TTC) is characterized by acute completely reversible regional left ventricle (LV) akinesia and decreased tracer uptake in the akinetic region on semi-quantitative perfusion imaging. The latter may be due to normoperfusion of the akinetic mid/apical area and basal hyperperfusion. Our aim was to examine abnormalities of perfusion in TTC, and we hypothesized that basal hyperperfusion is the primary perfusion abnormality in the acute state. METHOD AND RESULTS Twenty-five patients were diagnosed with TTC due to (i) acute onset of symptoms, (ii) typical apical ballooning, (iii) absence of significant coronary disease, and (iv) complete remission on 4-month follow-up. The patients underwent coronary angiography (CAG), echocardiography, cardiac magnetic resonance imaging (CMR), and (13)NH3/(82)Rb positron emission tomography (PET) in the acute state and-except CAG-on follow-up. Patients initially had severe heart failure, mid/apical oedema but no infarction, and a rise in cardiac biomarkers. On initial perfusion PET imaging, eight patients appeared to have normal, whereas 17 patients had impaired LV perfusion. In the latter, flow in the basal region was increased in the acute state (1.5 ± 0.1 vs. 1.2 ± 0.1 mL/g/minRPP-corrected, P < 0.01), whereas midventricular (1.7 ± 0.1 vs. 1.6 ± 0.1 mL/g/minRPP-corrected, P = 0.21) and apical (1.4 ± 0.1 vs. 1.5 ± 0.1 mL/g/minRPP-corrected, P = 0.36) flow was unchanged between acute and follow-up, and within normal range. CONCLUSION Our results suggest an abnormal LV perfusion distribution in the acute state of TTC with basal hyperperfusion and a normoperfused akinetic region. The proportion of patients without visualized perfusion abnormalities in the acute state may represent a subgroup with fast remission.

Takotsubo-cardiomyopathy: A case of extremely fast recovery described by multimodality cardiac imaging

A 67-year-old male was admitted on the suspicionof STEMI due to chest pain after strenuous work, lateralST-elevation on ECG and troponin T 523 ng/L (ref.\50 ng/L). He had hypertension, hypercholesterolaemiaand was an ex-smoker but was otherwise healthy. Acutecoronary angiography showed no culprit lesion butapical ballooning on ventriculography (Figure 1A).Several image modalities were performed as part of aresearch protocol:Cardiac SPECT during resting conditions 15 hours afteradmission (Figure 1B) showed a relative perfusionreductionoftheapexandmidventricularpart,extent40%.Cardiac MRI 22 h after admission (Figure 1C) showedapical ballooning and LVEF 40% (ref. 56%-78%) andbasal hypercontractility, but no sign of infarction.Echocardiography 35 h after admission (Figure 1D)showed an akinetic apex and LVEF 50%.A second cardiac MRI 48 hours after admission(Fig. 1E) showed normalized LVEF 70%, but persis-tent apical hypokinesia and edema.N

Normal Myocardial Flow Reserve in HIV-Infected Patients on Stable Antiretroviral Therapy: A Cross-Sectional Study Using Rubidium-82 PET/CT.

AbstractStudies have found HIV-infected patients to be at increased risk of myocardial infarction, which may be caused by coronary microvascular dysfunction. For the first time among HIV-infected patients, we assessed the myocardial flow reserve (MFR) by Rubidium-82 (82Rb) positron emission tomography (PET), which can quantify the coronary microvascular function. MFR has proved highly predictive of future coronary artery disease and cardiovascular events in the general population.In a prospective cross-sectional study, HIV-infected patients all receiving antiretroviral therapy (ART) with full viral suppression and HIV-uninfected controls were scanned using 82Rb PET/computed tomography at rest and adenosine-induced stress, thereby obtaining the MFR (stress flow/rest flow), stratified into low ⩽1.5, borderline >1.5 to 2.0, or normal >2.0.Fifty-six HIV-infected patients and 25 controls were included. The HIV-infected patients had a mean age of 53 years (range 37–68 years) with 23% active smokers. The controls had a mean age of 52 years (range 36–68 years) and 26% active smokers. In the HIV-infected group 73% had a normal MFR, 17% borderline, and 10% low values of MFR. Among controls these values were 71%, 19%, and 10%, respectively (P = 0.99). However, the HIV-infected group had lower values of stress myocardial blood flow (MBF) (2.63 ± 0.09 mL/g/min vs 2.99 ± 0.14 mL/g/min; P = 0.03). We found no evidence of decreased MFR as assessed by 82Rb PET among HIV-infected patients on stable ART with full viral suppression compared with HIV-uninfected controls. We did notice a decreased MBF during stress.

The clinical value of cardiac sympathetic imaging in heart failure

The autonomic nervous system plays an important role in the pathology of heart failure. The single‐photon emission computed tomography tracer iodine‐123‐metaiodobenzylguanidine (123I‐MIBG) can be used to investigate the activity of the predominant neurotransmitter of the sympathetic nervous system, norepinephrine. Also, positron emission tomography tracers are being developed for the same purpose. With 123I‐MIBG as a starting point, this brief review introduces the modalities used for cardiac sympathetic imaging.

Myocardial perfusion of infarcted and normal myocardium in propofol-anesthetized minipigs using 82 Rubidium PET

Cardiac Rubidium-82 (82Rb) positron-emission-tomography (PET) is a good method for quantification of myocardial blood flow in man. Quantification of myocardial blood flow in animals to evaluate new treatment strategies or to understand underlying disease is also of great interest but raises some challenges. Animals, which have been anesthetized during PET acquisition, might react differently to used stress medications, and therefore difficulties might exist while evaluating the resulting PET images using standard software packages from commercial vendors optimized for human hearts. Furthermore propofol, used for anesthesia, can influence myocardial perfusion and coronary flow reserve due to its vasorelaxant effect, and interactions might exist between propofol and used stress agents, potentially affecting the result of the examination. We present cardiac 82Rb-PET studies performed in propofol-anesthetized minipigs with normal and infarcted myocardium stressed with both adenosine and dipyridamole. Despite the mentioned challenges, we were able to trace the small minipig heart with software designed for human cardiac PET and to achieve blood flow measurements comparable with results in humans with both adenosine and dipyridamole. We found dipyridamole to be a superior stress agent for this experimental setup. Finally, we were able to clearly identify the myocardial perfusion defect after an induced myocardial infarction.