P955Non-invasive mapping: what is the minimal number of electrodes needed to obtain a good spatial resolution of the activation map?

Introduction and aims

The 12-lead ECG is highly inaccurate for localization of the site of origin of supraventricular and ventricular arrhythmias.  Non-invasive mapping systems (ECGI) based on a high number of electrodes recording the electrical activity on the surface of the torso have already proven good accuracy for mapping different arrhythmic substrates. The aim of this study was to assess what is the minimal number of leads needed to obtain a precise mapping with the ECGI.

Methods

This study enrolled 14 patients (9 male, median age 50 (44-58) years) referred to our center for catheter ablation of premature ventricular contractions (PVC). Patients underwent pre-procedural ECGI using the epicardial and endocardial mapping system . This system uses the DICOM images from contrast computed tomography of the heart and up to 28 adhesive electrodes with 8 leads each, adding up to 224 body-surface leads. All patients underwent invasive electroanatomical mapping and ablation with the magnetic navigation system. We analysed the number of recording leads used to construct the non-invasive activation map of the PVCs and the accuracy and the spatial resolution of the map when comparing to the invasive map. We then reprocessed the exam, using progressively less leads until we only left the leads placed in the standard 12 lead ECG positions and evaluated the concordance with the invasive map as well as the spatial resolution. We considered an earliest activation site (EAS) area of 1 cm2 a good spatial resolution and using a ROC curve we calculated the minimal number of leads necessary to obtain a good spatial resolution.

Results

The median number of electrodes used for the initial map was 170 (138-177). Concordance between non-invasive and invasive site of origin occurred in 11 out of 14 patients. The results are presented in the Table. The minimal number of electrodes to have a good spatial resolution was 100. The area of EAS was significantly lower when using more than 100 leads, respectively 0.65 (0.5-1) cm2 versus 3 (1.6-5) cm2, p < 0.001.

Conclusions

The minimal number of leads to achieve a good spatial resolution was high.  Reducing the number of leads resulted in a significant decrease in spatial resolution and a lower concordance rate.

ECGI data Number of adhesive electrodes Median number of leads Amycard/Carto concordance Median area of EAS in the ECGI (cm2) Maximal nº electrodes 170 (138-177) 11/14 0.64 (0.5-0.9) 12 electrodes 76 (61-80) 11/14 1.6 (1.4-2.6) 6 electrodes (2 Ant, 2 Lat ,2 Post) 38 (32-44) 9/14 4.3 (3.2-5.4) 12 leads 12 0/14 - Ant anterior; Lat: lateral; Post: posterior; EAS: early activation site.

Abstract Figure. Area of EAS according to the N of leads

P5702Non-invasive epicardial and endocardial mapping in patients with idiopathic right ventricular outflow tract premature ventricular contractions: new insights into arrhythmia substrate

Background

It has been accepted for years that idiopathic premature ventricular contractions (PVCs) with origin in the right ventricular outflow tract (RVOT) are benign. They are thought to result from triggered activity and most studies do not describe abnormal findings during electroanatomical mapping

Dispersion of ventricular repolarization is associated with the susceptibility to ventricular arrhythmias and may indicate the presence of diseased myocardium. The activation recovery interval (ARI) has been used as a surrogate measure of ventricular action potential duration and refractory period.

Purpose

The aim of this study was to use the new non-invasive epicardial and endocardial mapping system (NEES) to study patients with RVOT PVCs in order to evaluate the ARI in the epicardium of RVOT during sinus rhythm (SR).

Methods

Non-invasive mapping was performed with the NEES, based on body surface electrocardiograms of a maximum of 224 electrodes and computed tomography imaging data. Unipolar electrograms were reconstructed on the epicardial and endocardial surfaces. Patients were excluded if they had structural heart disease, previous ablation or conduction abnormalities. ARI was defined as the interval between times of minimum derivative of the QRS and the maximum derivative of the T wave in the unipolar electrograms. We evaluated the ARI map in patients with RVOT PVCs and in a control group of patients without PVCs (Figure). We assessed the maximum value of ARI (Max ARI), the minimum value of ARI (Min ARI) and the difference between the Max ARI and the Min ARI (Diff ARI).

Results

We studied 8 patients with RVOT PVCs and 8 patients without PVCs.

The results are presented in the table.

Demographic and NEES data RVOT PVCs (n=8) Control (n=8) P value* Demographic data   Age in years, median (IQR) 53 (48–65) 59 (52–67) 0.536   Male gender, n (%) 4 (50) 6 (75) 0.608 NEES data   Max ARI in msec, median (IQR) 285 (236–331) 228 (197–298) 0.195   Min ARI in msec, median (IQR) 176 (138–192) 216 (185–255) 0.161   ARI diff in msec, median (IQR) 111 (83–147) 15 (4–34) <0.0001

NEES map

Conclusion

In this group of patients we found a significantly higher dispersion of the ARI measurements through the epicardium of the RVOT in patients with PVCs in comparison with patients without PVCs.

P6165Sex differences in compositional plaque volume progression in patients with stable coronary artery disease: observations from a serial CCTA registry

Background

It is unclear whether sex impacts the plaque volume (PV) progression in patients with stable coronary artery disease (CAD).

Purpose

To explore whether the total and compositional PV progression rate differ according to sex.

Methods

We performed a prospective multinational registry of consecutive patients who underwent serial CCTA at ≥2-year interval. Total and compositional PV at baseline and follow-up were quantitatively analysed and normalized using the analysed total vessel length. Multivariate linear regression models were constructed for each women and men.

Results

Of the 1,255 patients included (median CT interval 3.8 years), 543 were women and 712 were men. Women were older (62±9 years vs. 59±9 years, p<0.001) and had higher total cholesterol level (195±41mg/dL vs. 187±39mg/dL, p=0.002). Prevalence of hypertension, diabetes, and family history of CAD were not different (all p>0.05).

At baseline, men possessed greater total PV (131.5±230.5mm3 vs. 97.7±193.6mm3, p=0.005) and a higher prevalence of high-risk plaques (HRP) than women (31% vs. 20%, p<0.001). Annual total PV progression rate was greater in men, driven by the greater non-calcified PV progression (TABLE).

In multivariate analysis (TABLE), although total PV progression rate was not different, women were associated with greater calcified PV progression (β=2.83, p=0.004) but slower non-calcified PV progression (β=-3.39, p=0.008) and less development of HRP (β=-0.18, p=0.049) than men.

CCTA findings according to sex Univariate analysis Female Sex in Multivariable Analysis Women (n=543) Men (n=712) P β SE P Agatston CACS, /year 0.44±0.7 0.4±0.7 0.332 0.106 0.04 0.006 Total PVnormalized, mm3/year 14.7±23.4 17.8±26.2 0.026 -0.56 1.33 0.677 Calcified PVnormalized, mm3/year 10.5±21.5 10.0±19.1 0.670 2.83 0.98 0.004 Non-calcified PVnormalized, mm3/year 4.2±17.3 7.8±21.2 0.001 -3.39 1.28 0.008 Development of high-risk plaque*, n (%) 86 (15.8) 139 (19.5) 0.092 -0.18 0.09 0.049 In linear multivariate regression analysis adjusted with age, race, HTN, DM, family history, smoking, LDL, statin, anti-platelets, beta-blockers, and PV at baseline, women were associated with greater calcified PV progression and slower non-calcified PV progression. (High-risk plaque was defined as ≥2 of low-attenuation plaque, spotty calcification, and positive remodelling.)

Conclusion

In this large CCTA cohort, we found that the compositional PV progression differs according to sex. These findings, which are hypothesis generating, suggest that comprehensive plaque evaluation may contribute to further refine risk stratification according to sex.

Acknowledgement/Funding

This work was supported by the National Research Foundation of Korea funded by the Ministry of Science and ICT (Grant No. 2012027176).

P2722Optimizing diagnosis of obstrutive coronary artery disease by CT angiography and ischemia test: a randomized clinical trial

Aim

In patients with suspected coronary artery disease (CAD), computed tomographic angiography (CTA) may improve patient selection for invasive coronary angiography (ICA) as alternative to functional testing. However, the role of CTA in symptomatic patients after abnormal functional test is incompletely defined.

Methods and results

This randomized clinical trial conducted in single academic tertiary center selected 218 symptomatic patients (pts) with mild to moderately abnormal functional test referred to invasive coronary to receive either the originally intended ICA (n=103) or CTA (n=115). CTA interpretation and subsequent care decisions were made by the clinical team. Patients with high risk features on functional tests, previous acute coronary syndrome, previously documented CAD, chronic kidney disease (GFR <60 ml/min/1.73m2) or persistent atrial fibrillation were excluded. The primary endpoint was the percentage of ICA with no significant obstructive CAD (no stenosis ≥50%) in each group. Diagnostic and revascularization yields of ICA in either group were also assessed. Subjects averaged 68±9 years of age, 60% were male, 29% were diabetic. Nuclear perfusion stress test was used in 33.9% in CTA group and 31.1% in control group (p=0.655). Mean post (functional) test probability of obstructive CAD was 34%. Overall prevalence of obstructive CAD was 32.1%. In the CTA group, ICA angiography was cancelled by referring physicians in 83 of the pts (72.2%) after receiving CTA results. For those undergoing ICA, nonobstructive CAD was found in 5 pts (15.6%) in the CTA-guided arm and 60 (58.3%) in the usual care arm (P<0.001). Mean cumulative radiation exposure related to diagnostic work up was similar in both groups (6±14 vs 5±14mSv, P=0.152), but a greater cumulative contrast dose in the CTA-guided group (87.5±21 vs 77±40, p=0.026) was observed. Both diagnostic (84.4% vs 41.7, p<0.001) and revascularization (71.9% vs 38.8%, p=0.001) yields were significantly higher for CTA-guided ICA as compared to standard functional test-guided ICA.

Conclusions

In patients with suspected CAD and mild to moderately abnormal functional test, a diagnostic strategy including computed tomographic angiography as gatekeeper is effective and significantly improves diagnostic and revascularization yields of invasive coronary angiography.

Absence of microsatellite instability and BRAF (V600E) mutation in testicular germ cell tumors

Testicular germ cell tumors (TGCT) are the most common malignant neoplasm in young men. DNA mismatch repair deficiency can lead to microsatellite instability (MSI), an important mechanism of genetic instability. A mutation of the BRAF gene has been implicated in the pathogenesis of several solid tumors and has recently become an important therapeutic target. The role of MSI and BRAF gene mutation in TGCT, particularly in refractory disease, is poorly understood and reported findings are controversial. In this study, we aimed to determine the frequency and clinical impact of MSI status and BRAF mutations in TGCT. DNA was isolated from formalin-fixed paraffin embedded (FFPE) tissue from 150 TGCT cases. The MSI phenotype was evaluated using multiplex PCR for five quasimonomorphic mononucleotide repeat markers. Exon 15 of the BRAF oncogene (V600E) was analyzed by PCR, followed by direct sequencing. Sixteen percent of cases were considered to have refractory disease. In a small subset of cases (17 for MSI and 18 for BRAF), the quantity and quality of DNA recovery were poor and therefore, were unable to be analyzed. The remaining 133 TGCT cases showed a complete absence of MSI. Of the 132 cases successfully evaluated for BRAF mutations, all were V600E wild-type. In conclusion, despite a distinct response of testicular germ cell tumors to therapy, microsatellite instability, and the BRAF V600E mutation were absent in all testicular germ cell tumors tested in this study.

[Calcifying tendinitis of the rotator cuff with focal umeral osteolysis. Imaging features]

Calcifying tendinitis occurs most commonly in the rotator cuff tendons, particularly involving the supraspinatus tendon insertion, and is often asymptomatic. Cortical erosion secondary to calcifying tendinitis has been reported in multiple locations, including in the rotator cuff tendons. The authors report two cases of symptomatic calcifying tendinitis involving the infraspinatus tendon with cortical erosion with correlative radiographic, and MR findings. The importance of considering this diagnosis when evaluating lytic lesions of the humerus and the imaging differential diagnosis of calcifying tendinitis and cortical erosion are discussed.

[Calcifying tendinitis of the rotator cuff with focal umeral osteolysis. Imaging features.]

Calcifying tendinitis occurs most commonly in the rotator cuff tendons, particularly involving the supraspinatus tendon insertion, and is often asymptomatic. Cortical erosion secondary to calcifying tendinitis has been reported in multiple locations, including in the rotator cuff tendons. The authors report two cases of symptomatic calcifying tendinitis involving the infraspinatus tendon with cortical erosion with correlative radiographic, and MR findings. The importance of considering this diagnosis when evaluating lytic lesions of the humerus and the imaging differential diagnosis of calcifying tendinitis and cortical erosion are discussed.