P970 Significant differences in atrial structural and functional parameters leading to differing mechanisms of atrial fibrillation in athletes compared to non-athletes

Methods

36 endurance athletes in sinus rhythm, with a previous history of AF (ATH-AF) were compared to age and gender matched endurance athletes with no prior history of AF (ATH), non athletes with paroxysmal AF (NONATH-AF) and age and gender matched healthy controls (CONTROL). A detailed transthoracic echocardiogram was performed with all groups in sinus rhythm, with detailed left atrial (LA) and left ventricular (LV) measurements, including strain analysis.

Results

All athletes had increased LA and LV size when compared with healthy controls (Table 1). Non athletes with paroxysmal AF had increased LA size when compared with controls. However, indexed LA/LV ratio was preserved in athletes and similar to healthy individuals, whilst AF patients had significantly increased LA/LV ratio. Athletes with AF had higher e’ velocity and lower E/e’, whereas e’ was reduced and E/e’ elevated in non-athlete AF patients.

Athletes had impaired LA reservoir and contractile strain, and reduced LV global longitudinal strain (GLS) compared with healthy controls.

Conclusions

Compared to healthy controls, athletes have reduced LA and LV strain, with preserved LV diastolic function and LA/LV ratio. In contrast, altered diastolic function with differential increase in LA volume was observed in AF patients. The increased risk of AF in athletes is likely mediated by different mechanistic processes other than an atrial myopathy consequent to diastolic dysfunction as observed in non-athletes with AF.

Table 1. LA and LV parameters Parameter ATH-AF ATH NONATH-AF CONTROL P value LVEDV indexed (ml/m2) 84 ± 12 79 ± 14 57 ± 10 51 ± 13 <0.001 LVESV indexed (ml/m2) 35 ± 6 34 ± 7 25 ± 8 27 ± 33 0.02 LV ejection fraction (%) 58 ± 4 56 ± 4 56 ± 10 58 ± 8 0.586 LV global longitudinal strain (%) 19.2 ± 1.7 18.9 ± 2.1 21 ± 3.1 21.7 ± 2.9 <0.001 e’ vel (cm/s) 10 ± 2 10 ± 3 8 ± 2 9 ± 2 0.007 E/e’ 5.7 ± 1.3 5.9 ± 1.8 9.1 ± 3.3 7.5 ± 1.5 <0.001 LAV max indexed (ml/m2) 45 ± 11 43 ± 12 38 ± 11 27 ± 8 <0.001 Indexed LAV/LVEDV ratio 0.5 ± 0.1 0.6 ± 0.2 0.7 ± 0.2 0.5 ± 0.1 <0.001 LA reservoir strain (%) 27.2 ± 4.8 28.2 ± 3.7 27.9 ± 8.4 33.2 ± 7.0 <0.001 LA conduit strain (%) 14.2 ± 4.5 14.4 ± 4.0 14.9 ± 5.5 16.6 ± 6.3 0.182 LA contractile strain (%) 13.0 ± 3.1 13.8 ± 3.6 13.0 ± 5.1 16.6 ± 3.1 <0.001 LV = left ventricular, LAV = left atrial volume, LA = left atrial

P1504 Inter-vendor comparison of left atrial 2-dimensional strain using multilayer analysis

BACKGROUND

Left atrial strain (LAS) is increasingly being accepted as a marker of left atrial function. Different vendors utilise different techniques of measuring LAS in echocardiography.

AIMS

To determine the difference between multilayer endocardial and mid-myocardial measurements of LA strain on General Electric (GE) Echopac compared to the TOMTEC system which tracks endocardial strain.

METHODS

Peak reservoir left atrial strain (LAS) was measured on 50 healthy controls using the two different echocardiographic software packages. GE Echopac (v201) 2D-speckle tracking echocardiography technique (LV package) was used to measuremid-myocardial (GE-mid) and endocardial (GE-endo) LAS. This was compared to LAS measurement using TOMTEC (v4.6) which uses an endocardial tracking technique. LAS was measured in 4ch and 2ch views and average biplane strain measurement was obtained.

RESULTS

The mean of GE-mid LAS was 36.3 ± 6.3%, GE-endo LAS was higher with a mean of 44.1 ± 8.0%, while TOMTEC LAS was 42.1 ± 6.3 %. GE-mid and GE-endo LAS correlated well with TOMTEC LAS (r = 0.9, p < 0.001 for both). On Bland-Altman Analysis, GE-mid LAS measurements were systematically lower than TOMTEC LAS (mean difference -5.77), whereas GE-endo LAS had no systematic bias (mean difference 1.99).

CONCLUSIONS

Mid-myocardial peak reservoir left atrial strain, which is routinely measured using GE Echopac software, systematically underestimates LAS as compared to TOMTEC LAS or GE endocardial LAS. This suggests that serial follow up of LAS measurements for patients should be performed on the same software.

P1783 Concealed structural abnormalities detected by 2D speckle tracking strain echocardiography persist post ablation in patients with idiopathic ventricular arrhythmias

Background

Idiopathic ventricular arrhythmias (IVA) occurs in patients without overt heart disease. 2D speckle tracking strain echocardiography parameters, including global longitudinal strain (GLS) and mechanical dispersion (MD), have been shown to predict ventricular arrhythmias. It is unclear if the abnormalities are due to structural substrate abnormality, or substrate abnormality consequent to electrical alterations. Aim: We sought to assess whether patients with IVA have impaired left ventricular (LV) strain indices, and if so, whether these persist following successful treatment with radiofrequency ablation (i.e. correction of electrical alteration). Methods: 2D strain analysis was performed (in sinus rhythm) in 23 consecutive patients with IVA (no structural heart disease by cardiac magnetic resonance imaging (MRI); Group A) prior to electrophysiological mapping/ablation, and compared to 23 age and gender matched healthy controls (Group B). Follow up echocardiography and multiday Holter monitoring was performed 12 months post ablation. Results: Baseline characteristics were similar for indexed LV end diastolic volume (EDV) and ejection fraction (EF) (p = 0.1 for both) (Table 1). LV GLS was lower (p = 0.03) and LV MD was increased (p = 0.002) in the IVA group prior to treatment. At follow up, 18 patients (78%) (Group C) remained free of ventricular arrhythmias – in these patients, LV GLS improved and was similar to controls (p = 0.217); however, LV MD remained significantly increased at 12 months compared to controls (p = 0.009). In the 5 patients (22%) (Group D) that continued to have ventricular arrhythmias at follow up, both LV GLS (p = 0.04) and LV MD (p = 0.008) remained significantly impaired compared to controls. Conclusion: Despite demonstrable absence of structural abnormalities with cardiac MRI, 2D strain can detect subtle alterations in myocardial contraction heterogeneity. Furthermore, 12 months post successful ablation treatment, the increase in MD persists. This suggest the presence of subtle substrate abnormality that results in IVA. In uncured patients, both myocardial deformation parameters remain impaired, suggesting the need for close future surveillance of these patients. Long term follow up with greater number of patients is required to further validate these findings.

Table 1. Echocardiographic parameters Group Indexed LVEDV (ml/m2) LVEF (%) LV GLS (%) LV MD (ms) IVA (Group A) 55 ± 15 61 ± 5 -19.9 ± 3* 44 ± 12* Controls (Group B) 54 ± 14 64 ± 7 -21.2 ± 2 33 ± 9 Group C 12 months follow up -21.7 ± 3 42 ± 11* Group D 12 month follow up -19.8 ± 2* 43 ± 11* * denotes p < 0.05

Synthesis of K–Pd doped NiCo2O4−δ by reactive calcination route for oxidation of CO–CH4 emissions from CNG vehicles

The present study is devoted to formulating a doped spinel catalyst by a novel route of calcination for the oxidation of the CO–CH₄ mixture emitted from compressed natural gas (CNG) vehicles.

The longest tumor diameter in one dimension as a predictor for skeletal metastasis in renal cell carcinoma

INTRODUCTION

Renal cell carcinoma (RCC) comprises a diverse group of malignant neoplasms that have multifarious histopathological features and biological behavior. One-third of RCC patients develops skeletal metastasis with a poor 5-year survival rate. Data explaining how some of these tumors show sooner bony metastasis than expected is sparse. The objective of this study was to identify whether tumor size can act as a predictor of bony metastases among patients of RCC.

MATERIALS AND METHODS

We retrospectively reviewed contrast enhanced computed tomography (CECT) scan and clinical records of 66 patients with RCC, who fulfilled specified inclusion criteria. Patients who had bony metastasis at the time of presentation were selected as case and those without skeletal metastasis were referred to as controls. Receiver operating characteristic (ROC) curve analysis was used to determine the appropriate cut-off value for tumor size, which was measured as the longest tumor diameter (LTD) in one-dimensional (1D).

RESULTS

Of the 66 patients selected, 30% developed bone metastasis. The tumor size of RCCs significantly correlated with the presence of skeletal metastasis in our study. None of the patients with 1D LTD <4.8 cm on CECT were found to have skeletal metastasis. ROC analysis revealed that the accuracy of the LTD in predicting bone metastasis was high with an area under ROC curve of 0.823. A cut-off value of 7.5 cm had a sensitivity of 78.9% and specificity of 80.9%.

CONCLUSION

The 1D LTD with a cut-off value of 7.5 cm, at the time of presentation is an important predictor of skeletal metastasis. The result of this study may have role in triage of patients into a subgroup which mandates more aggressive treatment and monitoring.

Phase II trial of post-operative radiotherapy with concurrent cisplatin plus panitumumab in patients with high-risk, resected head and neck cancer

BACKGROUND

Treatment intensification for resected, high-risk, head and neck squamous cell carcinoma (HNSCC) is an area of active investigation with novel adjuvant regimens under study. In this trial, the epidermal growth-factor receptor (EGFR) pathway was targeted using the IgG2 monoclonal antibody panitumumab in combination with cisplatin chemoradiotherapy (CRT) in high-risk, resected HNSCC.

PATIENTS AND METHODS

Eligible patients included resected pathologic stage III or IVA squamous cell carcinoma of the oral cavity, larynx, hypopharynx, or human-papillomavirus (HPV)-negative oropharynx, without gross residual tumor, featuring high-risk factors (margins <1 mm, extracapsular extension, perineural or angiolymphatic invasion, or ≥2 positive lymph nodes). Postoperative treatment consisted of standard RT (60-66 Gy over 6-7 weeks) concurrent with weekly cisplatin 30 mg/m² and weekly panitumumab 2.5 mg/kg. The primary endpoint was progression-free survival (PFS).

RESULTS

Forty-six patients were accrued; 44 were evaluable and were analyzed. The median follow-up for patients without recurrence was 49 months (range 12-90 months). The probability of 2-year PFS was 70% (95% CI = 58%-85%), and the probability of 2-year OS was 72% (95% CI = 60%-87%). Fourteen patients developed recurrent disease, and 13 (30%) of them died. An additional five patients died from causes other than HNSCC. Severe (grade 3 or higher) toxicities occurred in 14 patients (32%).

CONCLUSIONS

Intensification of adjuvant treatment adding panitumumab to cisplatin CRT is tolerable and demonstrates improved clinical outcome for high-risk, resected, HPV-negative HNSCC patients. Further targeted monoclonal antibody combinations are warranted.

REGISTERED CLINICAL TRIAL NUMBER

NCT00798655.