Casper Mihl

Background: Stress perfusion cardiac magnetic resonance imaging (MRI) enables accurate detection of myocardial ischemia. While contrast injection parameters, particularly iodine delivery rate, are known to influence image quality in CT, their impact in cardiac MRI remains insufficiently studied. This study aimed to evaluate the effect of different gadolinium-based contrast agent (GBCA) injection rates on objective and subjective image quality in perfusion cardiac MRI in patients with suspected ischemic heart disease. Methods: Ninety patients scheduled for a stress perfusion cardiac MRI were retrospectively included and allocated to 3 groups based on the GBCA injection rate used (eg, group 1: 6 mL/s, group 2: 4 mL/s, and group 3: 2 mL/s). Blood-pool signal intensity was extracted on a frame-by-frame basis to generate signal-intensity time curves. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated for all relevant regions, including SNR _ischemia , SNR _blood , SNR _myocardium , CNR _{ischemia–blood} , CNR _{myocardium–blood} , and CNR _{ischemia–myocardium} . Subjective image quality was scored on a 5-point Likert scale, blindly assessed in consensus by 2 cardiovascular radiologists. Results: Blood-pool peak intensity was the highest in the group with flow rates of 6 mL/s. Peak signal intensity was for the 6, 4, and 2 mL/s group, respectively, 17525±3616, 15213±3416, and 15534±2990 a.u. ( P =0.019) and post hoc comparison demonstrated a significant difference between the 6 mL/s and 4 mL/s group ( P =0.027). No significant differences in signal intensity of the myocardium, blood pool and the infarcted region were found between groups ( P =0.475, 0.399 and 0.519, respectively). Image noise was significantly higher in group 1 compared to group 3 ( P value=0.036). SNR of myocardium, blood, and ischemia was not significantly different between groups ( P =0.525, 0.595, and 0.453, respectively). CNR for ischemia-blood, myocardium-blood and ischemia-myocardium were the highest in group 3, but not significantly different ( P =0.373, 0.896, and 0.346, respectively). Subjective image quality and reader confidence were not significantly different between groups ( P values of 0.985 and 0.842). Although contrast quality demonstrated a statistically significant difference across groups ( P =0.026), this finding was not considered clinically relevant. Conclusion: Higher GBCA injection rates resulted in higher blood-pool peak enhancement, yet did not translate into significant differences in objective image and subjective image quality. Lower injection rates appear sufficient to achieve adequate myocardial perfusion imaging, suggesting a plateau in image quality in which increasing flow rates do not show added benefit.

Cardiac fibrosis is a key disease hallmark of dilated cardiomyopathy (DCM) and is associated with a risk of malignant arrhythmias and sudden cardiac death. Fibrosis can be the earliest sign of disease in asymptomatic family members carrying pathogenic variants, making timely recognition essential. Although echocardiography is often used for family screening, conventional echocardiography cannot assess myocardial tissue characteristics such as fibrosis. Cardiac magnetic resonance imaging (CMR), the reference standard for detecting myocardial fibrosis, provides tissue characterization but is challenging to be used as a first-line screening for all at-risk family members. Shear wave elastography (SWE) using high-frame rate echocardiography is an emerging technique that enables assessment of myocardial stiffness as a surrogate for fibrosis. The VISUALIZE-DCM trial is an investigator-initiated, single-center prospective study that evaluates SWE as a triage tool for CMR to detect myocardial fibrosis, and to determine whether increased myocardial stiffness is an early feature of genetic DCM. In this study, both naturally occurring and acoustic generated shear wave speeds (SWS) are assessed using high-frame rate imaging. Natural shear waves arise during valvular closure, whereas generated shear waves are induced by the acoustic radiation force. Myocardial stiffness measurements derived from SWS will be obtained in patients with established DCM, their at-risk family members, and healthy volunteers. SWE findings will be compared with fibrosis patterns on CMR, evaluated for their ability to detect early disease development in relatives, and contrasted with reference values from healthy controls to determine their potential clinical utility in DCM screening and risk stratification.

Aims: Cardiovascular magnetic resonance (CMR) could be considered as first diagnostic test in patients with suspected non-ST-elevation acute coronary syndrome (NSTE-ACS), since up to one-third do not have obstructive coronary artery disease (CAD). This meta-analysis aimed to investigate (i) the diagnostic accuracy of CMR to detect obstructive CAD and NSTE-ACS, and (ii) the prognostic value of CMR in patients with suspected NSTE-ACS. Methods and results: Pubmed, Embase, and Cochrane Library were searched (30 November 2024) for eligible studies. To determine the diagnostic accuracy of CMR prior to invasive coronary angiography, sensitivity, specificity, and likelihood ratios (LR+/−) were calculated for each endpoint. Data were pooled using a bivariate random-effects model. This meta-analysis was pre-registered in PROSPERO (CRD42024625306). Sixteen studies with 1386 patients were included. The pooled sensitivity and specificity to detect obstructive CAD (eight studies) were 85% (95%CI 78–91%) and 73% (95%CI 57–85%). The pooled LR+ and LR− were 3.20 (95%CI 1.78–5.73) and 0.20 (95%CI 0.11–0.36). The pooled sensitivity and specificity to diagnose NSTE-ACS (five studies) were 83% (95%CI 73–89%) and 89% (95%CI 72–96%). The pooled LR+ and LR− were 7.45 (95%CI 2.77–20.02) and 0.20 (95%CI 0.13–0.30). Finally, the pooled sensitivity and specificity for prognosis based on ACS-related outcomes (four studies) were 98% (95%CI 42–100%) and 85% (95%CI 65–95). The pooled LR+ and LR− were 6.55 (95%CI 2.45–17.54) and 0.03 (95%CI 0–1.54). Conclusion: CMR can detect obstructive CAD and diagnose NSTE-ACS with excellent pooled sensitivity and specificity. CMR findings are strongly associated with clinical outcome in patients with suspected NSTE-ACS.

A Bayesian diagnostic test accuracy meta-analysis of nine studies demonstrated the diagnostic accuracy of photon-counting detector coronary CT angiography, as compared with invasive coronary angiography, at the patient, vessel, and segment levels.

Objectives: The definitions of periprocedural myocardial infarction (PMI) after coronary artery bypass grafting (CABG) are heavily debated. A European Association for Cardiothoracic Surgery (EACTS)-endorsed international survey was conducted to evaluate current clinical practices and to reach a consensus-based agreement on the diagnostic characteristics required for a potential future PMI definition. Methods: The questionnaire complied with the CHERRIES guideline. A pilot version underwent iterative testing. The final version was distributed to all members of EACTS and allied specialties. The questionnaire evaluated definitions, biomarkers, and required diagnostic accuracy and was distributed between August-November 2024. Results: The questionnaire was completed by 175 respondents (surgeons: 71.4%, cardiologists: 20.6%, intensivists: 5.1%, other: 2.9%) from 29 countries. A specific definition of PMI was used by 46.4% of respondents (Universal Definition of Myocardial Infarction [UDMI]-4: 67.4%, Society of Cardiovascular Angiography and Interventions [SCAI]: 16.3%, second Academic Research Consortium [ARC-2]: 6.1%, other: 10.2%). Respondents identified biomarker concentrations defining PMI with supporting (imaging) evidence (high-sensitivity cardiac troponin T [hs-cTnT]: 489 ng/L, high-sensitivity cardiac troponin I [hs-cTnI]: 425 ng/L, CKMB-mass: 90ug/L, CKMB-activity: 100 U/L) and without (hs-cTnT: 931 ng/L, hs-cTnI: 1458 ng/L, CKMB-mass: 100ug/L, CKMB-activity: 300UL). The lowest acceptable sensitivity and specificity thresholds for a future definition were 95% [90%-95%] and 90% [80%-95%], respectively, while sensitivity was deemed more important than specificity (79.8% vs 20.2%, P < .001). Conclusions: The use of PMI definitions varies widely, though UDMI-4 is most frequently employed. Our findings highlight the need for a standardized, CABG-specific PMI definition with robust diagnostic accuracy to enable consistent diagnoses and a common clinical language.

Aims: Several contradictory definitions have been proposed for the diagnosis of periprocedural myocardial infarction (PMI) after coronary artery bypass grafting (CABG). The aim of this study was to assess the prevalence of PMI and to identify the definition of PMI with the most relevant prognostic impact. Methods and results: In this systematic review and meta-analysis, the search was conducted in thee electronic databases (MEDLINE & PubMed Central, Cochrane Library, Embase). The primary definitions of interest comprised the universal definition of myocardial infarction (UDMI; UDMI-3/4) and Society for Cardiovascular Angiography and Interventions (SCAI) definition. The primary outcomes were the prevalence of PMI and its prognostic impact, expressed in hazard ratios (HRs) and 95% confidence intervals (CIs). The frequentist framework was employed for the primary analysis, and a secondary analysis was performed under a Bayesian framework. Ten studies were included (n = 21 203 patients). The prevalence of PMI was 17.5% (95%CI 9.5–29.8%) according to SCAI, and 3.2% (95%CI 1.6–6.2%) according to UDMI-3/4. The pooled HR of the SCAI definition for freedom from all-cause mortality was 1.60 (95%CI 1.18–2.16) and the HR was 2.54 (1.62–4.00) for UDMI-3/4 (P-for-interaction = 0.097). The posterior probability of exceeding an HR of 1 was >99% for both definitions, while the probability of the UDMI-3/4 exceeding the mean HR of SCAI was 96.4%. The results were robust across sensitivity analyses. Conclusion: The prevalence of PMI is markedly higher when diagnosed according to SCAI criteria in CABG patients. The UDMI criteria define PMI with the most relevant prognostic impact in CABG patients.

Photon-counting detector computed tomography (PCD-CT) has emerged as a revolutionary technology in CT imaging. PCD-CT offers significant advancements over conventional energy-integrating detector CT, including increased spatial resolution, artefact reduction and inherent spectral imaging capabilities. In cardiac imaging, PCD-CT can offer a more accurate assessment of coronary artery disease, plaque characterisation and the in-stent lumen. Additionally, it might improve the visualisation of myocardial fibrosis through qualitative late enhancement imaging and quantitative extracellular volume measurements. The use of PCD-CT in cardiac imaging holds significant potential, positioning itself as a valuable modality that could serve as a one-stop-shop by integrating both angiography and tissue characterisation into a single examination. Despite its potential, large-scale clinical trials, standardisation of protocols and cost-effectiveness considerations are required for its broader integration into clinical practice. This narrative review provides an overview of the current literature on PCD-CT regarding the possibilities and limitations of cardiac imaging.