Abstracts

Poster Walk: Cardiac Imaging

DOI: https://doi.org/10.4414/cvm.2019.02051
Publication Date: 31.05.2019
Cardiovasc Med. 2019;22:w02051

P21‒P25

Joint Annual Meeting 2019 of the Swiss Society of Cardiology and the Swiss Society of Cardiac Surgery

P21

Indexed coronary volume - a potential novel low-dose CCTA derived predictor for cardiovascular events

G. Benetos, M. Goncalves, E. Von Felten, G. Rampidis, O. Clerc, D. Benz, C. Gebhard, T. Fuchs, A. Pazhenkottil, P. Kaufmann, R. Buechel, C. Gräni

Department of Nuclear Medicine, University of Zurich, Zurich, Switzerland

Introduction: Little is known about the long-term predictive performance of CCTA-derived coronary volumes and mid-diastolic left ventricular (LV) mass.In the present study we assessed the long-term prognostic value of coronary volumes and mid-diastolic LV mass as novel potential imaging predictors derived from low-dose prospectively ECG-triggered CCTA.

Methods: Consecutive patients with suspected or known coronary artery disease, referred for low-dose CCTA, were included. Patients with previous revascularization were excluded. The following parameters were evaluated: calcium score, segment involvement score (SIS: 1 point for each coronary segment with presence of plaque), coronary volume, mid-diastolic LV mass and coronary volume indexed to LV mass. Major adverse cardiovascular events (MACE) were defined as all-cause death, non-fatal myocardial infarction and revascularization (PCI or CABG). The association between CCTA measures and the occurrence of events was quantified using cox regression hazard and Kaplan Meier analysis.

Results: A total of 147 consecutive patients were included in the study. Of them, 93 (63.3%) were male and 79 (53.7%) hat one or more traditional cardiovascular risk factors. There was a weak but statistical significant inverse correlation between indexed coronary volume and both calcium score (R=-0.3, p=0.01) and SIS (R=-0.24, p=0.005). After a median follow-up of 5.8 years 30 MACE occurred in 25 patients, including 3 deaths, 26 revascularizations and 1 non-fatal myocardial infarction. In univariate cox regression hazard analysis calcium score (HR=12.69, 95% CI 2.99-53.83, p< 0.001), SIS (HR=1.66, 95% CI 1.43-1.94, p< 0.001), LV mass (HR=1.02, 95% CI 1.01-1.03, p=0.007) and indexed coronary volume (HR=0.89, 95% 0.82-0.96, p=0.004) were associated with outcome. In multivariate analysis, indexed coronary volume, remained an independent predictor for MACE when adjusted for traditional risk factors and SIS (HR=0.93, 95% CI 0.87-1.00, p=0.05), while LV mass did not reach statistical significance (p=0.46). By ROC curve analysis, a value of 21.85 mm3/gr was defined as optimal cutoff for indexed coronary volume. In Kaplan Meier plots, patients with low indexed coronary volume (< 21.85 mm3/gr) showed higher event rates (log rank p< 0.001) compared to high indexed coronary volume (≥ 21.85 mm3/gr).

Conclusions: Indexed coronary volume, derived from low-dose CCTA, independently predicts cardiovascular events.

P22

Diagnostic accuracy of coronary artery calcium score for immediate prediction of myocardial ischaemia

O.F. Clerc1, F. Caobelli2, P. Haaf1, M.J. Zellweger1

1Cardiology, 2Nuclear Imaging, University Hospital Basel, Basel, Switzerland

Introduction: Coronary artery calcium score (CACS) is an excellent predictor of long-term adverse cardiac events. However, little is known about its diagnostic value and thresholds for immediate prediction of myocardial ischaemia. Therefore, we assessed the diagnostic accuracy of CACS to predict myocardial ischaemia in a large cohort of patients with single-photon emission computed tomography (SPECT).

Methods: All consecutive patients undergoing SPECT myocardial perfusion imaging between August 2015 and November 2018 at our centre were enrolled. Patients with known coronary artery disease, coronary anomaly, cardiomyopathy, cardiac transplantation, or missing imaging data were excluded. Ischaemia was defined as a summed difference score (SDS) ≥4 in SPECT, and severe ischaemia as SDS ≥8. CACS was measured from low-dose computed tomography scans using the Agatston method. Area under the curve (AUC) was compared for prediction models based on CACS or on cardiovascular risk factors (CVRF) with symptoms. Receiver operating characteristic (ROC) analysis was used to calculate sensitivity, specificity, positive and negative predictive values of CACS for ischaemia at pre-specified cut-offs.

Results: Of 3916 patients, 1752 were excluded. Thus, 2164 patients with both CACS and SPECT were included. Mean age was 68.2 ±11.2 years and median CACS was 132 Agatston units (AU). Among our patients, 388 (18%) had ischaemia and 129 (6%) severe ischaemia. For ischaemia prediction, CACS had an AUC of 0.765 (0.746-0.783) and was superior to the CVRF-based model (AUC 0.599 [0.578-0.619], P < 0.0001, Figure P22-1). CACS 0 AU had 97% sensitivity and 97% negative predictive value for ischaemia. CACS 100 AU had 84% sensitivity and 94% negative predictive value. But CACS 1000 AU had 90% specificity and 45% positive predictive value. Analysis of CACS for severe ischaemia yielded similar results, with AUC 0.812 (0.795-0.828) and superiority over the CVRF-based model (AUC 0.644 [0.623-0.664], P < 0.0001). CACS 0 AU had 100% sensitivity and 100% negative predictive value for severe ischaemia. CACS 100 AU had 92% sensitivity and 99% negative predictive value. But CACS 1000 AU had 88% specificity and 20% positive predictive value.

Conclusion: CACS values can be used not only to predict long-term cardiac events, but also for immediate diagnostic purposes. In particular, a CACS ≤100 AU has an excellent negative predictive value for myocardial ischaemia.

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P22-1: ROC curves for ischaemia prediction models.

P23

Computed tomography angiography for the diagnosis of coronary artery disease among patients undergoing transcatheter aortic valve implantation

A. Depierre1, O. Muller1, A. Nicolas2, A. Topolsky2, D. Meier1, S.D. Qanadli2, C. Achtari3, S. Fournier1

1Cardiology, 2Radiology, 3Gynecology and Obstetrics, Lausanne University Center Hospital, Lausanne, Switzerland

Introduction: Coronary artery disease (CAD) is frequently seen in patients suffering from severe aortic valve stenosis (AS), as both pathologies share the same pathophysiology. In a transcatheter aortic valve implantation (TAVI) work-up, patients beneficiate from both computed tomography angiography (CTA) and invasive coronary angiography (ICA). Some studies evaluated the performance of CTA to diagnose CAD among patients undergoing TAVI and showed interesting results. Nevertheless, data remain scarce and this diagnostic method is not validated in this population. In this context, we thought to evaluate the diagnostic performance of CTA to diagnose CAD among patients selected for TAVI.

Methods: A total of 199 patients that had a TAVI in the Lausanne University Hospital between the 1st of June 2013 and the 31st of December 2017 were retrospectively included. Exclusion criteria were coronary artery bypass graft prior to CTA and unavailable CTA images. Finally, 127 patients were included. Two independent radiologists - blinded for ICA report - were asked to read the CTA of these patients and to indicate the presence of ≥50% and ≥70% stenosis in the 4 main coronary vessels. Their evaluation was then compared with ICA reports and analyses were performed at vessel and patient levels.

Results: A total of 342 vessels were analyzable. Based on ICA, significant CAD (at least 1 ≥50% stenosis) was present in 49 (38.6%) patients. Severe CAD (≥70% stenosis) was found in 29 (22.8%) patients. Sensitivity, specificity, positive predictive value, negative predictive value and accuracy of CTA to diagnose significant CAD were 81.1%, 87.9%, 44.8%, 97.5% and 87.1% at vessel level using the cut-off of 50% and 42.8%, 97.8%, 56.3%, 96.3% and 94.4% for severe CAD, using the cut-off of 70%. At patient level, sensitivity, specificity, positive and negative predictive values were respectively 84.6%, 64.6%, 56.4% and 88.6% for significant CAD.

Conclusion: Pre-TAVI CTA shows good performance to rule out significant and severe CAD and could be used as a gatekeeper for ICA. Positive findings on CTA should be confirmed with ICA given the low positive predictive value.

P24

Adaptation of left atrial function in acute and chronic ST-segment elevation myocardial infarction

A.G. Pavon1, P.G. Masci2, A. Bermano3, A. Vaxman4, C. Gotsman5, N. Lauriers6, D. Rodrigues7, P. Monney6, E. Eeckhout2, O. Muller2, J. Schwitter8

1Centre de la Resonance Magnetique, Centre Hospitalier Universitaire Vaudois, 2Centre Universitaire Vaudois, Lausanne, Switzerland, 3The Blavatnik School of Computer Science, Tel Aviv, Israel, 4Department of Information and Computing Sciences, Utrecht, Belgium, 5Ying Wu College of Computing, New-Jersey Institute of Technology, New jersey, IA, United States, 6Centre Hospitalier Universitaire Vaudois, 7Radiology, Centre Hospitalier Universitaire Vaudois, 8Centre de la Resonance Magnetique, Centre Universitaire Vaudois, Lausanne, Switzerland

Background: The left atrium (LA) is exposed to left ventricular (LV) pressure and volume changes. LA functional adaptation in acute ST-segment elevation myocardial infarction (STEMI) and during healing is not known.

Materials and methods: We examine LA changes in 31 patients with a first episode of STEMI. Patients underwent a cardiac magnetic resonance examination (CMR). 21 patients had a CMR within 15 days from STEMI (acute-STEMI), while 17 patients were studied after ≥40 days from the acute event (chronic-STEMI). 8 patients had 2 CMR examinations in both, the acute-STEMI and chronic-STEMI situation. For accurate LA function analyses, a compressed sensing (CS) cine pulse sequence was used (acquiring 3 short-axis and 2 long-axis 2D slices in a single breath-hold) and data were re-constructed in a 3D non model- based format (as previously published, Figure P24-1A, 1B). Active and passive LA emptying fraction (as % of pre-emptying LA volume) were calculated according the formula in Figure P24-1. Total indexed conduit LA volume is LA maximum - LA minimum volume (per body surface area). All data are presented as mean ± standard deviation.

Results: Patients (n=31) were not known for previous cardiovascular events (age 65.9 ±14.5, 58% male) and all patients had primary percutaneous coronary intervention/stenting of the occluded coronary artery. In 21 patients CMR was performed after 3.7±3.1 days from the acute event (=acute-STEMI). In 17 patients (chronic-STEMI) CMR was performed 75±34 days after the acute event. Active LA emptying fraction (%) decreased from the acute to the chronic state (43.3±18.9% vs 12.9±8.8% p=0.003), while passive LA emptying fraction (%) increased (9.0±4.9 vs 19.2±8.8%, p < 0.001; Figure P24-1C). Total indexed conduit LA volume was not different between the two populations (acute vs chronic: 25.0±8.1 vs 23.4±10.7ml/m2; p=ns). Among the 31 patients, 8 patients had CMR examinations at both time points (i.e. acute-STEMI and chronic-STEMI). Comparable changes were observed in these 8 patients (acute vs chronic LA active emptying fraction: 75.3±15.0 vs 43.0±24.2%, p=0.002; LA passive emptying fraction: 24.7±15.0 vs 57.2± 24.1%, p=0.008).

Discussion: In the acute STEMI situation, the LA can adapt its active emptying performance in the presence of compromised passive emptying. This might reflect a compensatory mechanism to maintain adequate LV filling in the acute STEMI. This increased active LA emptying decreases in the chronic state after infarction.

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P24-1.

P25

Strain parameters using CMR feature tracking are associated with fibrosis and not with edema in patients with suspected myocarditis

A. Stark1, K. Fischer2, S.A. Erne1, S.J. Obrist1, M. Steigner3, D.P. Guensch2, A. Aghayev4, R. Blankstein4, S. Windecker1, M. Jerosch-Herold3, R.Y. Kwong3, C. Gräni1,3

1Department of Cardiology, 2Department of Anaesthesiology and Pain Medicine, Inselspital, Bern University Hospital, University of Bern, Berne, Switzerland, 3Non-invasive Cardiovascular Imaging, Cardiovascular Division, Department of Medicine, 4Non-invasive Cardiovascular Imaging, Department of Radiology, Harvard Medical School, Boston, MA, United States

Introduction: Myocarditis is a leading cause of dilated cardiomyopathy. Cardiovascular magnetic resonance imaging (CMR) is the primary imaging tool in the clinical setting of suspected myocarditis, with the ability to noninvasively characterize the myocardial tissue. Late gadolinium enhancement (LGE) is a marker of focal fibrosis, T1 mapping and extracellular volume (ECV) fraction strengths are detection of diffuse fibrosis, while T2-weighted imaging is a marker for edema.Feature tracking CMR (FT-CMR) is a quantitative method that uses cine CMR to measure different strain parameters. FT-CMR has recently been shown to have diagnostic and prognostic value; however, it has not yet been investigated in myocarditis. We aimed to analyze the association of FT-CMR with tissue characterization in suspected myocarditis.

Method: Patients with clinically suspected myocarditis and no coronary artery disease who underwent a contrast enhanced CMR exam were enrolled. The presence of focal fibrosis was assessed in LGE anddiffuse fibrosis in native T1 and ECV images. Myocardial edema was depicted bythe T2 ratio of the signal intensity of the myocardium compared to skeletal muscle. An independent reader measured myocardial deformation using circumferential peak strain (PS), systolic strain rate (sSR), diastolic strain rate (dSR), time to peak strain (TTP) and displacement (DPL). Global FT parameters were then compared to tissue characterization results (figure P25-1).

Results: 129 patients (46±15 years) were included, with a mean LGE size of 3.7±7.0%, mean native T1 of 1006±75ms (at 1.5T), T2 ratio of 1.8±0.7 and ECV of 30.9±5.4%.Mean PS was 13.8±5.3%, sSR -0.85±0.34/s, dSR 0.84±0.43/s. TTP 311.80±67.12ms and DPL 0.95±2.25mm.PS and sSR showed a significant correlation with LGE, T1 and ECV, while dSR only showed a correlation with LGE and a trend with native T1 and ECV (figure 2, p< 0.001). TTP, DPL were not associated with tissue characterization. No association was found between T2 ratio and FT-CMR.

Conclusions: In patients with suspected myocarditis, circumferential left ventricular strain obtained by FT-CMR is associated with the presence of fibrosis, both focal and diffuse. However, myocardial edema was not associated with global left ventricular strain parameters. Investigation of a larger population, regional strain parameters and association of FT-CMR with outcome is needed to assess its potential role for contrast-free markers in patients with suspected myocarditis.

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P25-1.
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P25-2.

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