Stephan Fluechter

Extent of late gadolinium enhancement detected by cardiovascular magnetic resonance correlates with the inducibility of ventricular tachyarrhythmia in hypertrophic cardiomyopathy

BackgroundMyocardial fibrosis is frequently identified in patients with hypertrophic cardiomyopathy (HCM). The aim of this study was to investigate the role of myocardial fibrosis detected by late gadolinium-enhancement (LGE) cardiovascular magnetic resonance (CMR) as a potential arrhythmogenic substrate in HCM. We hypothesized that the extent of LGE might be associated with the inducibility of ventricular tachyarrhythmias (VT) during programmed ventricular stimulation (PVS).MethodsWe evaluated retrospectively LGE CMR of 76 consecutive HCM patients, of which 43 presented with one or more risk factors for sudden cardiac death (SCD) and were therefore clinically classified as high-risk patients. Of these 43 patients, 38 additionally underwent an electrophysiological testing (EP). CMR indices and the extent of LGE, given as the % of LV mass with LGE were correlated with the presence of risk factors for SCD and the results of EP.ResultsHigh-risk patients had a significant higher prevalence of LGE than low-risk patients (29/43 [67%] versus 14/33 [47%]; p = 0.03). Also the % of LV mass with LGE was significantly higher in high-risk patients than in low-risk patients (14% versus 3%, p = 0.001, respectively). Of the 38 high- risk patients, 12 had inducible VT during EP. LV function, volumes and mass were comparable in patients with and without inducible VT. However, the % of LV mass with LGE was significantly higher in patients with inducible VT compared to those without (22% versus 10%, p = 0.03). The prevalence of LGE was, however, comparable between HCM patients with and those without inducible VT (10/12 [83%] versus 15/26 [58%]; p = 0.12). In the univariate analysis the % of LV mass with LGE and the septal wall thickness were significantly associated with the high-risk group (p = 0.001 and 0.004, respectively). Multivariate analysis demonstrated that the extent of LGE was the only independent predictor of the risk group (p = 0.03).ConclusionsThe extent of LGE in HCM patients correlated with risk factors of SCD and the likelihood of inducible VT. Furthermore, LGE extent was the only independent predictor of the risk group. This supports the hypothesis that the extent of fibrosis may serve as potential arrhythmogenic substrate for the occurrence of VT, especially in patients with clinical risk factors for SCD.

Takotsubo Cardiomyopathy (Acute Left Ventricular Apical Ballooning Syndrome) Occurring in the Intensive Care Unit

ObjectiveDiagnosis of Takotsubo cardiomyopathy (also known as stress cardiomyopathy or acute left ventricular apical ballooning syndrome) can be challenging in patients who are being treated for other diseases in the intensive care unit, because symptoms could erroneously be attributed to the underlying disease or patients may not experience symptoms due to analgesia and sedation. The aim of our study was to assess clinical features of Takotsubo cardiomyopathy occurring in the intensive care unit.DesignProspective observational study.SettingUniversity hospital.PatientsSix consecutive patients diagnosed with Takotsubo cardiomyopathy who were being treated for other diseases in the intensive care unit.InterventionsNone.Measurements and main resultsSudden hemodynamic deterioration (i.e., sudden hypotension, tachycardia or drop in monitored stroke volume) requiring vasopressor support was the presenting symptom in five of the six patients. Only one patient was able to report angina-like chest pain, all others were unable to experience symptoms due to analgesia and sedation. The electrocardiogram was abnormal in all patients upon diagnosis, demonstrating either ST-segment elevation (n = 2) and/or T-wave inversion (n = 5). Mild elevation of cardiac enzymes disproportionate to the extent of wall motion abnormalities on left ventriculography was present in all patients. All patients survived their acute event.ConclusionsSudden hemodynamic deterioration requiring vasopressor support and/or ECG abnormalities consisting of ST-segment elevation, ST-segment depression or T-wave inversion may be the presenting symptom of Takotsubo cardiomyopathy in the intensive care unit and should be included in the diagnostic algorithm.

Noninvasive determination of cardiac output by the inert-gas-rebreathing method--comparison with cardiovascular magnetic resonance imaging.

Background: An easy, noninvasive and accurate technique for measuring cardiac output (CO) would be desirable for the diagnosis and therapy of cardiac diseases. Innocor, a novel inert-gas-rebreathing (IGR) system, has shown promising results in smaller studies. An extensive evaluation in a larger, less homogeneous patient collective is lacking. Methods: We prospectively assessed the accuracy and reproducibility of CO measurements obtained by IGR in 305 consecutive patients as compared to the noninvasive gold standard, cardiovascular magnetic resonance (CMR) imaging. Results: Bland-Altman analysis showed a good correspondence of the two methods for CO measurement with an average deviation of 0.2 ± 1.0 liters/min (mean ± SD) and a good reproducibility with a mean bias of 0.2 ± 0.5 liters/min. The accuracy of the present measurements at rest was significantly better in the physiological range than in higher or lower CO ranges. The error levels set forth by current recommendations were exceeded. Conclusion: The data show that IGR measurements are easy to perform and show good agreement with CMR; however, the technique appears to be less accurate in extreme CO ranges at rest. The clinical importance of the IGR method remains to be proven by further studies.

Bioimpedance Analysis Parameters and Epicardial Adipose Tissue Assessed by Cardiac Magnetic Resonance Imaging in Patients With Heart Failure

There is increasing evidence that body composition should be considered as a systemic marker of disease severity in congestive heart failure (CHF). Prior studies established bioelectrical impedance analysis (BIA) as an objective indicator of body composition. Epicardial adipose tissue (EAT) quantified by cardiac magnetic resonance (CMR) is the visceral fat around the heart secreting various bioactive molecules. Our purpose was to investigate the association between BIA parameters and EAT assessed by CMR in patients with CHF. BIA and CMR analysis were performed in 41 patients with CHF and in 16 healthy controls. Patients with CHF showed a decreased indexed EAT (22 ± 5 vs. 34 ± 4 g/m2, P < 0.001) and phase angle (PA) (5.5° vs. 6.4°, P < 0.02) compared to healthy controls. Linear regression analysis showed a significant correlation of CMR indexed EAT with left ventricular ejection fraction (LV‐EF) (r = 0.56, P < 0.001), PA (r = 0.31, P = 0.01), total body muscle mass (TBMM) (r = 0.41, P = 0.001), fat‐free mass (FFM) (r = 0.30, P = 0.02), and intracellular water (ICW) (0.47, P = 0.0003). Multivariable analysis demonstrated that LV‐EF was the only independent determinant of indexed EAT (P < 0.0001). Receiver operating characteristic curve analysis indicated good predictive performance of PA and EAT (area under the curve (AUC) = 0.86 and 0.82, respectively) with respect to cardiac death. After a follow‐up period of 5 years, 8/41 (19.5%) patients suffered from cardiac death. Only indexed EAT <22 g/m2 revealed a statistically significant higher risk of cardiac death (P = 0.02). EAT assessed by CMR correlated with the BIA‐derived PA in patients with CHF. EAT and BIA‐derived PA might serve as additional prognostic indicators for survival in these patients. However, further clinical studies are needed to elucidate the prognostic relevance of these new findings.

A hybrid approach for quantification of aortic valve stenosis using cardiac magnetic resonance imaging and echocardiography

SummaryWe replaced Dopplerderived stroke volume in the continuity equation (method A) by either right heart catheterizationderived stroke volume (method B) or cardiovascular magnetic resonance–derived stroke volume (method C) to calculate aortic valve area in 20 consecutive patients with moderate or severe aortic stenosis. Comparison of both hybrid methods (methods B and C) by Bland–Altman analysis showed a mean difference near zero, a spread within two standard deviations and very similar limits of agreement. More importantly, all patients were classified into the same category of severity by both methods.

Delayed hyperenhancement in a case of Takotsubo cardiomyopathy

Takotsubo cardiomyopathy (TTC) consists of an acute onset of transient akinesia of various parts of the left ventricle (apex and mid in classical TTC, mid and base in the variant form), without significant coronary artery stenosis, often accompanied by chest pain, dynamic reversible ST-T segment abnormalities and elevation of cardiac enzymes disproportionate to the extent of akinesia. Contrast-enhanced cardiovascular magnetic resonance (CMR) is a useful adjunct in the diagnostic work up of patients with TTC. Delayed hyperenhancement on gadolinium-enhanced CMR, which is indicative of active inflammation (e.g. myocarditis) or myocardial fibrosis (e.g. myocardial infarction), is usually absent in patients with TTC. In this report we present the case of a 46-years old women with TTC who had an extensive area of apical and midventricular akinesia and in whom gadolinium-enhanced CMR demonstrated a small area of subendocardial delayed hyperenhancement. A gadolinium-enhanced CMR performed 6 weeks later exhibited complete reversal of all wall motion abnormalities and an identical area of subendocardial delayed hyperenhancement.

Visual estimation of the extent of myocardial hyperenhancement on late gadolinium-enhanced CMR in patients with hypertrophic cardiomyopathy.

AIM So far different approaches have been used to quantify late gadolinium enhancement (LGE) in patients with hypertrophic cardiomyopathy (HCM), but there is no general consensus on the gold standard, since histological data are scarce. The aim of our study was to investigate whether the determination of LGE in patients with HCM using a semiquantitative score based on the 17-segment model is feasible and has comparable accuracy to manual planimetry. METHODS Forty-two patients with HCM underwent LGE cardiovascular magnetic resonance imaging. Determination of LGE by planimetry based on visual assessment was used as reference standard. Then the extent of LGE was assessed using a semiquantitative score based on the standard left ventricular 17-segment model. Each segment was scored for the distribution of LGE. The resulting summed score expressed as percentage of the maximum possible score was thereafter compared with the manual planimetric evaluation of LGE, expressed as a percentage of the left ventricular myocardial area. RESULTS In 28 patients (66%), LGE was present. There was a good correlation between the semiquantitative score and the planimetric approach (r=0.89; y=0.819x+2.45; standard error of estimation=2.327; P<.0001). Additionally, the Bland-Altmann plot showed a high concordance between the two approaches (mean of the difference +1.7%). The inter- and intraobserver limits of agreement and the coefficients of repeatability based on measurements with the semiquantitative score of the extent of LGE were superior to planimetric measurements. Besides, the time requirement for the LGE determination using the semiquantitative score was found to be significantly reduced compared to manual planimetry (median 2 vs. 10 min). CONCLUSIONS Thus, a reliable global index of the size of the LGE is feasible and can easily be obtained from visual assessment with a semiquantitative score of the extent of the hyperenhancement.

Validation of the Peak to Mean Pressure Decrease Ratio as a New Method of Assessing Aortic Stenosis Using the Gorlin Formula and the Cardiovascular Magnetic Resonance-Based Hybrid Method

Background: We sought to validate the recently introduced peak to mean pressure decrease ratio (PMPDR), using the Gorlin formula and a hybrid method which combines cardiovascular magnetic resonance (CMR)‐derived stroke volume with transaortic Doppler measurements to calculate aortic valve area (AVA). Methods: Data analysis in 32 patients with severe (AVA <= 0.75 cm2) or moderate aortic stenosis who had prospectively been entered into our aortic stenosis database. Results: Gorlin‐derived AVA was 0.61 ± 0.10 cm2 in severe and 0.92 ± 0.14 cm2 in moderate aortic stenosis (P < 0.01). Corresponding values for PMPRD were 1.61 ± 0.10 and 1.73 ± 0.18, respectively (P < 0.05). Sensitivity, specificity, positive and negative predictive values for PMPDR <1.5 to predict severe aortic stenosis were 0.12, 0.92, 0.67, and 0.44 as assessed by the Gorlin formula. Conclusions: Using the Gorlin formula as the reference standard, our study confirms results of a previously reported study on the performance of PMPDR for assessment of aortic stenosis.