The Role of Electrocardiographic Markers for Predicting Atrial Fibrillation in Patients with Acute Ischemic Stroke: Data from the BIOSIGNAL Cohort Study

BACKGROUND AND AIMS

P-wave abnormalities in the 12-lead electrocardiogram (ECG) have been associated with a higher risk of acute ischemic stroke (AIS) as well as atrial fibrillation (AF). This study aimed to assess pre-determined ECG criteria during sinus rhythm in unselected AIS patients and their value for predicting newly diagnosed atrial fibrillation (NDAF) after hospital admission.

METHODS

P-wave alterations were measured on 12-lead ECG on admission in all consecutively enrolled patients without known AF between October 2014 and 2017. The outcome of interest was NDAF, identified by prolonged electrocardiographic monitoring within one year after the index AIS. Univariable and multivariable logistic regression was applied to assess the magnitude and independence of the association between pre-selected ECG markers and NDAF. The discriminatory accuracy was evaluated with the area under the receiver operating characteristic curve (AUC), and the incremental prognostic value was estimated with the net reclassification index.

RESULTS

NDAF was detected in 87 (10%) of 856 patients during a follow-up of 365 days. Out of the pre-selected ECG parameters, advanced interatrial block (aIAB) and PR interval in lead II were independently associated with NDAF in univariable regression analysis. Only aIAB remained a significant predictor in multivariable analysis. Adding aIAB to the best-performing multivariable regression model improved the discriminatory accuracy to predict NDAF from an AUC of 0.78 (95%-CI 0.77-0.80) to 0.81 (95%-CI 0.80-0.83, p < 0.001).

CONCLUSION

aIAB is independently and highly associated with NDAF in patients with AIS, has high inter-rater reliability, and therefore may be helpful to refine diagnostic work-up to search for AF in AIS.

Assessment of Artificial Intelligence in Echocardiography Diagnostics in Differentiating Takotsubo Syndrome From Myocardial Infarction

Importance

Machine learning algorithms enable the automatic classification of cardiovascular diseases based on raw cardiac ultrasound imaging data. However, the utility of machine learning in distinguishing between takotsubo syndrome (TTS) and acute myocardial infarction (AMI) has not been studied.

Objectives

To assess the utility of machine learning systems for automatic discrimination of TTS and AMI.

Design, Settings, and Participants

This cohort study included clinical data and transthoracic echocardiogram results of patients with AMI from the Zurich Acute Coronary Syndrome Registry and patients with TTS obtained from 7 cardiovascular centers in the International Takotsubo Registry. Data from the validation cohort were obtained from April 2011 to February 2017. Data from the training cohort were obtained from March 2017 to May 2019. Data were analyzed from September 2019 to June 2021.

Exposure

Transthoracic echocardiograms of 224 patients with TTS and 224 patients with AMI were analyzed.

Main Outcomes and Measures

Area under the receiver operating characteristic curve (AUC), accuracy, sensitivity, and specificity of the machine learning system evaluated on an independent data set and 4 practicing cardiologists for comparison. Echocardiography videos of 228 patients were used in the development and training of a deep learning model. The performance of the automated echocardiogram video analysis method was evaluated on an independent data set consisting of 220 patients. Data were matched according to age, sex, and ST-segment elevation/non-ST-segment elevation (1 patient with AMI for each patient with TTS). Predictions were compared with echocardiographic-based interpretations from 4 practicing cardiologists in terms of sensitivity, specificity, and AUC calculated from confidence scores concerning their binary diagnosis.

Results

In this cohort study, apical 2-chamber and 4-chamber echocardiographic views of 110 patients with TTS (mean [SD] age, 68.4 [12.1] years; 103 [90.4%] were female) and 110 patients with AMI (mean [SD] age, 69.1 [12.2] years; 103 [90.4%] were female) from an independent data set were evaluated. This approach achieved a mean (SD) AUC of 0.79 (0.01) with an overall accuracy of 74.8 (0.7%). In comparison, cardiologists achieved a mean (SD) AUC of 0.71 (0.03) and accuracy of 64.4 (3.5%) on the same data set. In a subanalysis based on 61 patients with apical TTS and 56 patients with AMI due to occlusion of the left anterior descending coronary artery, the model achieved a mean (SD) AUC score of 0.84 (0.01) and an accuracy of 78.6 (1.6%), outperforming the 4 practicing cardiologists (mean [SD] AUC, 0.72 [0.02]) and accuracy of 66.9 (2.8%).

Conclusions and Relevance

In this cohort study, a real-time system for fully automated interpretation of echocardiogram videos was established and trained to differentiate TTS from AMI. While this system was more accurate than cardiologists in echocardiography-based disease classification, further studies are warranted for clinical application.

Dynamics of recent thymic emigrants in pediatric recipients of allogeneic hematopoetic stem cell transplantation

After allogeneic hematopoietic stem cell transplantation (allo-HSCT), the recurrence of recent thymic emigrants (RTE) and self-tolerant T cells indicate normalized thymic function. From 2008 to 2019, we retrospectively analyzed the RTE-reconstitution rate and the minimal time to reach normal age-specific first percentiles for CD31⁺CD45RA⁺CD4⁺T cells in 199 pediatric patients after allo-HSCT for various malignant and non-malignant diseases. The impact of clinically significant graft-versus-host disease (GvHD), age at transplantation, underlying disease and cumulative area under the curve of busulfan on RTE-reemergence was assessed in multivariable longitudinal analysis. RTE-reconstitution (coefficient -0.24, 95% CI -0.33 to -0.14, p < 0.001) was slowed down by GvHD and the time to reach P1 was significantly longer (Event Time Ratio 1.49, 95% CI 1.25 to 1.78, p < 0.001). Older age at transplantation was also associated with a slower RTE-reconstitution (coefficient -0.028, 95% CI -0.04 to -0.02, p < 0.001) and time to reach P1 was significantly longer (Event Time Ratio 1.03, 95% CI 1.02 to 1.05, p < 0.001). RTE-reconstitution velocity was not influenced by underlying disease or cumulative busulfan exposure. In summary, duration until thymic reactivation was independent of both conditioning intensity and underlying disease and was negatively influenced by older age and GvHD.

Impact of a new motion-correction algorithm on image quality of low-dose coronary CT angiography in patients with insufficient heart rate control

RATIONALE AND OBJECTIVES

Prospective electrocardiogram (ECG) triggering allows coronary computed tomography angiography (CCTA) scanning with low radiation dose but requires heart rates below 63 beats/min. We assessed the impact of a novel vendor-specific motion-correction algorithm on image quality and interpretability of low-dose CCTA acquired despite insufficient heart rate control.

MATERIALS AND METHODS

In 40 patients undergoing CCTA for the assessment of known or suspected coronary artery disease who did not reach the target heart rate below 63 beats/min despite β-blockade before prospective low-dose scanning, the temporal acquisition window was increased (80 ms additional padding). The new algorithm detects and integrates vessel path and velocity from adjacent cardiac phases for motion correction. Two blinded observers assessed image quality on a 4-point Likert scale (1, nonevaluative; 2, reduced but evaluative; 3, good; and 4, excellent) and the fraction of interpretable segments (score 2 or more) using motion correction versus standard reconstruction.

RESULTS

Image reconstruction with motion correction resulted in an increased median coronary artery image quality score (excellent interobserver agreement, κ = 0.85) compared to standard reconstruction (3.4 vs. 3.0, P < .001). Consequently, motion-corrected reconstruction significantly improved the overall interpretability of coronary arteries (from 78% to 88%, P < .001). Estimated mean effective radiation dose was 2.3 ± 0.8 mSv.

CONCLUSIONS

A novel, vendor-specific, motion-corrected, reconstruction algorithm improves image quality and interpretability of prospectively ECG-triggered low-dose CCTA despite insufficient heart rate control.

Coronary computed tomography angiography with model-based iterative reconstruction using a radiation exposure similar to chest X-ray examination

Aims

To evaluate the feasibility and image quality of coronary computed tomography angiography (CCTA) acquisition with a submillisievert fraction of effective radiation dose using model-based iterative reconstruction (MBIR) for noise reduction.

Methods and results

In 42 patients undergoing standard low-dose (100–120 kV; 450–700 mA) and additional ultra-low-dose CCTA (80–100 kV; 150–210 mA) reconstructed with MBIR, segmental image quality was graded on a four-point scale [(i): non-evaluative, (ii): good, (iii): adequate, and (iv): excellent]. Signal-to-noise ratio (SNR) was calculated dividing left main artery (LMA) and right coronary artery (RCA) attenuation by the aortic root noise. Over a wide range of body mass index (18–40 kg/m²), the estimated median radiation dose exposure was 1.19 mSv [interquartile range (IQR): 1.07–1.30 mSv] for standard and 0.21 mSv (IQR: 0.18–0.23 mSv) for ultra-low-dose CCTA (P < 0.001). The median image quality score per segment was 3.5 (IQR: 3.0–4.0) in standard CCTA vs. 3.5 (IQR: 2.5–4.0) in ultra-low dose with MBIR (P = 0.29). Diagnostic image quality (scores 2–4) was found in 98.7 vs. 97.8% coronary segments (P = 0.36). Introduction of MBIR for ultra-low-dose CCTA resulted in a significant increase in SNR (P < 0.001) for LMA (from 15 ± 5 to 29 ± 7) and RCA (from 14 ± 4 to 27 ± 6) despite 82% dose reduction.

Conclusion

Coronary computed tomography angiography acquisition with diagnostic image quality is feasible at an ultra-low radiation dose of 0.21 mSv, e.g. in the range reported for a postero-anterior and lateral chest X-ray.

A PET/CT-follow-up imaging study to differentiate takotsubo cardiomyopathy from acute myocardial infarction

Takotsubo cardiomyopathy (TTC) is still an under-recognized disease and little data exists on the coexistence of TTC and obstructive coronary artery disease. Our patient case of an 80-year-old female lady highlights the impact of a positron emission tomography/computed tomography (PET/CT) follow-up imaging study to delineate this unique entity from acute coronary syndrome (ACS). Furthermore, we show for the first time that coronary flow reserve and myocardial blood flow is globally impaired in TTC and not only restricted to the non-contracting parts. This indicates a global microcirculatory impairment effect of the heart in the acute stage of TTC. Our case also demonstrates that a transient metabolic defect is also involved in this disease. Follow-up imaging by PET/CT in our patient case unmasked TTC and facilitated to exclude the differential diagnosis of ACS.

Impact of cardiac magnetic resonance imaging on human lymphocyte DNA integrity

AIMS

Magnetic resonance (MR) imaging is widely used for diagnostic imaging in medicine as it is considered a safe alternative to ionizing radiation-based techniques. Recent reports on potential genotoxic effects of strong and fast switching electromagnetic gradients such as used in cardiac MR (CMR) have raised safety concerns. The aim of this study was to analyse DNA double-strand breaks (DSBs) in human blood lymphocytes before and after CMR examination.

METHODS AND RESULTS

In 20 prospectively enrolled patients, peripheral venous blood was drawn before and after 1.5 T CMR scanning. After density gradient cell separation of blood samples, DNA DSBs in lymphocytes were quantified using immunofluorescence microscopy and flow cytometric analysis. Wilcoxon signed-rank testing was used for statistical analysis. Immunofluorescence microscopic and flow cytometric analysis revealed a significant increase in median numbers of DNA DSBs in lymphocytes induced by routine 1.5 T CMR examination.

CONCLUSION

The present findings indicate that CMR should be used with caution and that similar restrictions may apply as for X-ray-based and nuclear imaging techniques in order to avoid unnecessary damage of DNA integrity with potential carcinogenic effect.

First experience with monochromatic coronary computed tomography angiography from a 64-slice CT scanner with Gemstone Spectral Imaging (GSI)

BACKGROUND

New technology combining dual-energy CT with the latest gemstone detectors for spectral imaging (GSI) can be used to synthesize monochromatic images that mimic images as if different monochromatic x-ray sources were used.

OBJECTIVE

The aim of the study was to evaluate the optimal combination of monochromatic image energy and adaptive statistical iterative reconstruction (ASiR) for monochromatic reconstruction of coronary CT angiography (CTA) images with the use of GSI.

METHODS

Twenty consecutive patients underwent coronary CTA on a GSI capable 64-slice CT scanner (Discovery CT 750 High Definition, GE Healthcare). In 7 sets of monochromatic images (60, 65, 70, 75, 80, 90, and 110 keV; each with increasing contributions of ASiR, ie, 0%, 20%, 40%, 60%, and 80%; n = 35 reconstructions per patient), signal-to-noise (aortic root) and contrast-to-noise (left main artery) ratios were assessed. Signal-to-noise ratio, contrast-to-noise ratio, and image quality (graded on a 5-point Likert scale) were assessed in all above monochromatic reconstructions and compared with the respective standard (conventional polychromatic) image.

RESULTS

Compared with conventional polychromatic images, reconstructions with 60 keV and 80% ASiR showed the highest improvement in contrast-to-noise (144%; P < 0.001) and signal-to-noise ratio (173%; P < 0.001). Image quality reached a plateau at 65-75 keV with 40%-60% ASiR blending, yielding a maximal image quality score improvement of 50% compared with conventional imaging (P < 0.001).

CONCLUSION

In coronary CTA with low radiation technique (mean radiation dose, 1.8 ± 0.7 mSv), GSI with monochromatic reconstructions (65-75 keV) and ASiR (40%-60%) offers significant noise reduction and image quality improvement.

Persistent low thymic activity and non-cardiac mortality in children with chromosome 22q11.2 microdeletion and partial DiGeorge syndrome

A subgroup of patients with 22q11.2 microdeletion and partial DiGeorge syndrome (pDGS) appears to be susceptible to non-cardiac mortality (NCM) despite sufficient overall CD4(+) T cells. To detect these patients, 20 newborns with 22q11.2 microdeletion and congenital heart disease were followed prospectively for 6 years. Besides detailed clinical assessment, longitudinal monitoring of naive CD4(+) and cytotoxic CD3(+)CD8(+) T cells (CTL) was performed. To monitor thymic activity, we analysed naive platelet endothelial cell adhesion molecule-1 (CD31(+)) expressing CD45RA(+)RO(-)CD4(+) cells containing high numbers of T cell receptor excision circle (T(REC))-bearing lymphocytes and compared them with normal values of healthy children (n = 75). Comparing two age periods, low overall CD4(+) and naive CD4(+) T cell numbers were observed in 65%/75%, respectively, of patients in period A (< 1 year) declining to 22%/50%, respectively, of patients in period B (> 1/< 7 years). The percentage of patients with low CTLs (< P10) remained robust until school age (period A: 60%; period B: 50%). Low numbers of CTLs were associated with abnormally low naive CD45RA(+)RO(-)CD4(+) T cells. A high-risk (HR) group (n = 11) and a standard-risk (SR) (n = 9) group were identified. HR patients were characterized by low numbers of both naive CD4(+) and CTLs and were prone to lethal infectious and lymphoproliferative complications (NCM: four of 11; cardiac mortality: one of 11) while SR patients were not (NCM: none of nine; cardiac mortality: two of nine). Naive CD31(+)CD45RA(+)RO(-)CD4(+), naive CD45RA(+)RO(-)CD4(+) T cells as well as T(RECs)/10(6) mononuclear cells were abnormally low in HR and normal in SR patients. Longitudinal monitoring of naive CD4(+) and cytotoxic T cells may help to discriminate pDGS patients at increased risk for NCM.