Ranolazine has been found to prevent ventricular arrhythmias (VAs) during acute myocardial infarction (AMI). This study aimed to investigate its efficacy on VAs induced several days post-MI. For this purpose, 13 anesthetized rabbits underwent coronary artery ligation. Ten of these animals that survived AMI were reanesthetized 3 to 7 days later for electrophysiologic testing. An endocardial monophasic action potential combination catheter was placed in the right ventricle for simultaneous pacing and recording. Monophasic action potential duration, ventricular effective refractory period (VERP), and VAs induced by programmed stimulation were assessed. Measurements were performed during control pacing, and following an intravenous infusion of either a low-dose ranolazine (2.4 mg/kg, R1) or a higher dose ranolazine (4.8 mg/kg cumulative dose, R2). During control stimulation, 2 animals developed primary ventricular fibrillation (VF), 6 sustained ventricular tachycardia (sVT), and 2 nonsustained VT (nsVT). R1 did not prevent the appearance of VAs in any of the experiments; in contrast, it aggravated nsVT into sVT and complicated sVT termination in 2 of 6 animals. Sustained ventricular tachycardia cycle length and VERP were only slightly decreased after R1 (112 ± 5 vs 110 ± 6 ms and 101 ± 11 vs 98 ± 10 ms, respectively). R2 suppressed inducibility of control nsVT, VF, and sVT in 2 animals. In 4 animals with still inducible sVT, R2 significantly prolonged VT cycle length by 150 ± 23 ms ( P < .01), and VERP by 120 ± 7 ms ( P < .001) versus control. In conclusion, R2 exerted antiarrhythmic efficacy against subacute-MI VAs, whereas R1 rather aggravated than prevented these arrhythmias. Ventricular effective refractory period prolongation could partially explain the antiarrhythmic action of R2 in this rabbit model.

Funding Acknowledgements Type of funding sources: None. Background The relationship between the excessive supraventricular ectopic activity (ESVEA) and the subclinical atrial fibrillation (AF) in patients with cryptogenic stroke is yet not fully understood. Purpose The aim of this study is to examine the prognostic significance of ESVEA for the development of AF in those patients. Methods The study retrospectively included 124patients, hospitalized for a cryptogenic stroke between 2014 and 2015. Twenty-four hour inpatient Holter monitoring, was used to define ESVEA as the presence of ≥20 premature atrial complexes per hour (PACs/h), along with a duration of the longest run of supraventricular tachycardia (LSVR) ≥5 seconds. After approximately 5 years of follow-up, the patients were examined for AF. Results The remaining 111 patients(12 died and 1 was lost during follow-up) had a median age of 56 and 13 (11.71%) of them were diagnosed with AF (AF patients). The median value of CHA2DS2-VASc score was 3 and was similar for the two groups (p=0.252). Patients with AF had a significantly higher number of PACs/h and a longer duration of LSVR compared to nonAF patients (16.67 vs. 0.21, p&lt;0.001 and 3 vs. 0 seconds, p&lt;0.001, respectively). The existence of ESVEA was also significantly more prevalent among the AF patients (46.15%, 95% CI: 17.78% - 74.22%) compared to non-AF ones (6.1%, 95% CI: 1.3% - 10.7%, p&lt;0.001). ROC analysis revealed the high diagnostic test accuracy of both PACs/h and LSVR for AF. The area under the curve was 97.2% (p&lt;0.001) for PACs/h and 81.1% (p&lt;0.001) for LSVR. Conclusions Excessive atrial ectopy, detected with 24h inpatient Holter monitoring, is a significant indicator of future development of AF, in patients presenting originally with a cryptogenic stroke.

Funding Acknowledgements None Background/Introduction: Calculation of the LV and RV stroke volumes (SV) with the volumetric method can be useful for assessment of valvular regurgitant volumes and intracardiac shunt ratios. However, this method often yields significant differences between the estimated LV and RV SV even in healthy subjects. We hypothesized that this discrepancy can be largely due to the assumption of LV and RV outflow tract circularity which forms the basis of 2D derived areas. Purpose To assess if the use of 3D transoesophageal (TOE) derived LVOT and RVOT areas can improve the agreement between LV and RV stroke volumes using the volumetric approach in healthy subjects with no valvular abnormality or intracardiac shunt. Methods We studied 20 patients (9 Males, age: 51 ± 19 y) submitted to TOE for various reasons, who had normal cardiac anatomy and function and good quality 3D TOE LVOT and RVOT data. Two dimensional TOE measurements of the LVOT and RVOT diameters were made in a zoomed mid oesophageal long axis and short axis view respectively; using these measurements 2D TOE LVOT and RVOT derived areas were calculated assuming circularity. In a similar way, we calculated the 2D LVOT and RVOT areas using data from transthoracic echo (TTE) for each patient. Offline analysis of the 3D TOE data allowed direct planimetry of the LVOT and RVOT areas devoid of any geometric assumptions. Finally, calculation of the 2D TTE, 2D TOE and 3D TOE LV and RV stroke volumes were performed for each patient based on the acquired data. The difference between LV and RV stroke volume (which theoretically should be around zero) for each technique and for each patient was also calculated. Results The mean LV and RV SV for the whole cohort, did not differ significantly within each method: 2D-TTE. However, the mean absolute difference between LV and RV stoke volumes for each technique was significantly lower with the use of 3D TOE compared to both 2D TTE and 2D TOE. Mean values and dispersion of absolute differences for each method are shown in Figure 1. Conclusions Compared to 2D, use of direct 3D TOE RVOT and LVOT planimetry yielded significantly less difference between RV and LV stroke volumes in healthy individuals. This finding can have potential clinical implications for more accurate assessment of valvular regurgitant volumes or intracardiac shunts. The mean absolute difference LV-RV Absolute mean defference between LV and RV 95%ΔΕ F(2.38) p-value TTE 2D 18,65 ± 11,72 (13,2-24,1) 8.63 0.001 TOE 2D 13,45 ± 12,44 (7,6-19.3) 8.63 0.001 TOE 3D 6,45 ± 3,62 (4,8-8,1) 8.63 0.001 Abstract P1559 Figure. Bland Altaman Analysis

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Funding Acknowledgements Type of funding sources: None. Background/Introduction The treatment of ST-elevation myocardial infarction (STEMI) has considerably changed in recent years, with early, mainly transcatheter reperfusion therapy improving survival. However, left ventricular thrombus (LVT) is still reported as a relatively common complication especially in anterior STEMI. Two-dimensional transthoracic echocardiography (TTE) is the most commonly used diagnostic modality in this setting due to its wide availability and low cost but can lead to misdiagnoses. The use of ultrasound contrast agents has dramatically improved the visualization of cardiac chambers and thus detection of LVT. Purpose The purpose of this study was to assess the value of contrast echocardiography (CE) for the detection of apical LVT in a real-world population of patients with acute anterior myocardial infarction (MI) in the modern era. Methods The population of this prospective study consisted of consecutive patients presenting within a year with acute anterior MI in a tertiary hospital with capability of primary percutaneous coronary intervention (PCI). Patients with confirmed COVID-19 infection and/or current use of anticoagulant medication were excluded from the study. All patients underwent TTE without and with contrast within 7 days post-MI by an experienced cardiologist. CE was considered the reference standard. Results A total of 102 patients (mean age 61±13 years, 19% female) with anterior STEMI were prospectively recruited in our study. Ninety-eight patients underwent primary PCI, 3 patients underwent rescue PCI after unsuccessful thrombolysis, 1 patient underwent surgical revascularization. Two patients did not receive contrast agent (1 due to known hypersensitivity to contrast agent and 1 due to cardiogenic shock). Mean ejection fraction (EF) was 46% ± 10% in total population and was significantly lower in patients with LVT (42% ± 7% vs 47% ± 10%, p = 0.025). The incidence of confirmed LVT by CE was 28% (28/100) within 7 days post-MI. In total, 8 out of 28 LVT cases (28.5%) would have been missed using TTE without contrast within 7 days post-MI (sensitivity 71%, specificity 100%, positive predictive value 100% and negative predictive value 90%). Example of missed LVT on TTE without and with contrast (left and right panel respectively) is shown in Figure 1. Conclusions LVT is not uncommon after anterior STEMI in the modern era of primary PCI. LVT would have been missed in a significant proportion of patients with anterior STEMI if CE was not used, depriving these patients from the option of early anticoagulation treatment.