1244Feasibility, safety and efficacy of tailoring ablation index to left atrial wall thickness (lawt) during atrial fibrillation ablation. The Ablate By-LAW Study

Funding Acknowledgements

Dr Teres was funded by Swiss Heartrhythm Foundation

Introduction

Circumferential pulmonary vein isolation (PVI) has become a mainstay in the treatment of atrial fibrillation (AF). The utility of ablation index (AI) to dose radiofrequency delivery for the reduction of AF recurrences has already been proven with a target AI ≥ 400 at the posterior wall and ≥550 at the anterior Wall. Nevertheless, the left atrial wall is a thin, heterogeneous structure with an important inter and intra-patient variability of LAWT.

Objective

To determine if adapting AI to atrial wall thickness (AWT) is feasible, effective and safe during AF ablation.

Methods

Single-Center study that included 80 consecutive patients referred for a first paroxysmal AF ablation that was performed with a single catheter approach with the intention to reduce vascular access complication rate. All patients had a MDCT prior to the ablation procedure. LAWT maps were semi-automatically computed from the MDCT as the local distance between the LA endo and epicardium. All procedures were performed under general anesthesia with a high-rate low-volume ventilation protocol for obtaining higher catheter stability. The transeptal puncture was TEE-guided. During the procedure, the WT map was fused with the LA anatomy using CARTO-merge. LAWT was categorized into 1mm-layers and the AI was titrated to the local atrial WT as follows: Thickness < 1 mm (red): 300; 1-2 mm (yellow): 350; 2-3 mm (green): 400; 3-4 mm (blue): 450; > 4 mm (purple): 450 (Figure). Maximal inter-lesion distance was set at 6 mm. VisiTag settings were: catheter position stability: minimum time 3 s, maximum range 4 mm; force over time: 25%, minimum force 3 g; lesion tag size: 3 mm. Respiration training was not possible due to the high catheter stability.  The circumferential ablation line was designed in a personalized fashion to avoid thicker regions.

Results

80 patients [41 (51,2 %) male, age 60± 11 years] were included. Mean LVEF was 59 ± 5 %, Mean LA diameter 39,1 ± 5,8 mm, Mean LAWT was 1.36 ± 0.63 mm. Mean AI was 352 ± 36 on the RPVs and 356 ± 36 on the LPVs. Procedure time was 60,0 min (IQR 51-70). Fluoroscopy time was 58,5 s (35-97,5). First pass isolation was obtained in 72 (90%) of the RPVs and 75 (93,8%) of the LPVs.

Conclusions

the present study, assessing a novel, personalized protocol for radiofrequency titration during atrial fibrillation ablation, shows a high rate of first pass isolation with a lower need for RF energy delivery and lower procedure requirements, as compared to previous PV ablation protocols. Further studies are needed to evaluate the long-term results of this approach.

Abstract Figure. LAWT-map Visitag points with tailored AI

659Left atrial wall thickness evaluation during atrial fibrillation redo procedures

Funding Acknowledgements

Dr Teres was funded by Swiss Heartrhythm Foundation

Introduction

pulmonary vein (PV) reconnections due to gaps on circumferential ablation lines are responsible for atrial fibrillation recurrences after catheter ablation. We sought to analyze the local left atrial wall thickness (LAWT) of PV line gaps at AF redo ablation during real-time catheter positioning. LAWT was measured on the MDCT 3D reconstruction and fused with the LA anatomy using CARTO-merge.

Objective

To analyze the relationship between local reconnection gaps and the LAWT during AF redo procedures.

Methods

Single-Center cohort study that included 41 consecutive patients referred for AF redo procedure. All patients had a MDCT prior to the ablation procedure. LAWT maps were semi-automatically computed from the MDCT as the local distance between the LA endo and epicardium. Each PV line was subdivided into 8 segments and mean LAWT was computed. During the procedure, the local gap was defined as the earliest activation site at the reconnected segment of the circumferential PV line (Figure 1A & 1B).

Results

41 patients [31 (75.6%) male, age 60 ± 10 years] were included. Mean LAWT was 1.36 ± 0.20 mm. Mean PV circumferential line WT was higher in left PVs than in the right PVs 1.68 ± 0.57 vs. 1.31 ± 0.39 mm p < 0.001 respectively. Mean WT of the reconnected points was 44% higher than the mean WT of the segment where the reconnection was located. Mean reconnection point WT was at the 87th percentile of the circumferential line in the LPVs and at the 76th percentile in the RPVs. The reconnected point WT was higher in the LPVs than RPVs 2.13 ± 1.14 vs. 1.47 ± 0.48 mm p < 0.001 respectively.  The most frequent location for reconnections was the left anterior carina (71%), with a mean WT of 2.24 ± 0.91mm; and the right anterior carina (56%) with a mean WT of 1.57 ± 0.62mm (Figure 2A & 2B).

Conclusions

Reconnection points were more frequently present in the thicker segments of the PV circumferential line. The most frequently reconnected segment was the anterior carina in both right and left PVs. Atrial wall thickness maps derived from MDCT are useful to guide AF redo procedures.

Abstract Figure. 1) Activation & WT map; 2) Segment WT

P917 Additional value of atrial parameters evaluated by echocardiography on the scales of cardioembolic risk in atrial fibrillation

Background

Atrial morphological parameters may influence the presence of atrial thrombus, a factor strongly associated with cardiac thromboembolism, independently of those included in the CHA2DS2-VASc risk estimation scale in patients with a history of atrial fibrillation (AF). The aim of our study was to evaluate this possible association by transthoracic echocardiography (TTE).

Methods

Prospective multicenter study including 401 patients with a history of AF, in which a TTE and a transesophageal echocardiogram (TEE) were performed for evaluation of atrial thrombus between 2016-2019. The parameters included in the CHA2DS2-VASc scale, the heart rhythm at the time of the study and the anticoagulant treatment performed, as well as the atrial morphological parameters were collected.

Results

Twenty-three patients (6%) presented with atrial thrombus in TEE. The left atrial area (28 ± 6cm2 vs 33 ± 6cm2; p < 0.001), the presence of AF during the study (83% vs 17%; p = 0.002) and CHA2DS2-VASc (1.7 ± 1.5cm2 vs 3.0 ± 1.3cm2; p < 0.001) were associated with the presence of atrial thrombus. The left atrial area was a diagnostic predictor of atrial thrombus (area under the curve = 73%; p = 0.001): a value >30cm2 presented a sensitivity of 79% and a specificity of 70% to detect its presence. Logistic regression analysis, including heart rhythm during the study and anticoagulant treatment, showed that CHA2DS2-VASc (OR = 1.5; CI95%=1.1-1.9; p = 0.003) and left atrial area >30cm2 (OR = 5.2;CI 95% =1.7-16.0; p = 0.004) were independent predictors of atrial thrombus presence.

Conclusions

The left atrial area is associated with the presence of atrial thrombus in patients with a history of AF independently of the CHA2DS2-VASc scale, heart rhythm during the study, and anticoagulant treatment. This parameter should be evaluated to be included in the cardioembolic risk scales.

[Myocardial perfusion SPECT and isotopic ventriculography in obstructive and non-obstructive hypertrophic myocardiopathy]

OBJECTIVE

To evaluate the role of myocardial perfusion SPET and radionuclide ventriculography in patients with hypertrophic cardiomyopathy (HC).

METHODS

Exercise myocardial perfusion SPET with 99mTc-tetrofosmin and radionuclide ventriculography were performed in a consecutive series of 101 patients (54 15 years, 50 women, 55 with dynamic obstruction) diagnosed of HC by echo. Follow-up from the diagnosis was 9,9 6,7 years (1 to 28 years).

RESULTS

Thirty six percent of patients had perfusion defects (non reversible in 15 and reversible in 21). In non obstructive HC higher number of patients with non reversible defects (p = 0.01 was obseved and in patients with no reversible defects higher incidence of pathologic Q waves in ECG (p = 0.01), Higher ventricular volumes (p < 0.05), lower ejection fraction (p = 0,0001) and longer time to peak emptying velocity (p < 0.05). There were 4 cardiac deaths, 15 syncopes, 18 pacemakers and 6 myectomy. Ejection fraction was higher in patients with syncope (p = 0,034) and there was no isotopic variable predictive of mortality, pacemaker or myectomy.

CONCLUSIONS

Neither SPET nor radionuclide ventriculography have a prognostic role in patients with HC, but patients with syncope have higher values of ejection fraction. Patients with non reversible defects have higher rate of pathologic Q waves in ECG, higher ventricular volumes and lower ejection fraction. This is indicative of evolution to dilated form of HC.

[Myocardial SPET in hypertrophic cardiomyopathy]

INTRODUCTION AND OBJECTIVES

The aim of this study was to evaluate the diagnostic accuracy of myocardial SPET in patients with hypertrophic cardiomyopathy (HC).

PATIENTS AND METHODS

One hundred and six consecutive patients (aged 53 +/- 12 years, 50 women, 66 with dynamic obstruction) with an echocardiographic diagnosis of HC were studied with exercise-rest myocardial SPET with 99mTc-tetrofosmin. Forty-six (43%) of these patients had chest pain and in 31 (29%) a coronary angiography was performed. Fifty-six per cent of the patients were treated with beta-blockers and 23% with verapamil.

RESULTS

Angina during the exercise test was observed in only 8% of the patients. Perfusion defects were observed in 35% of the patients. Only 8 (26%) out of the 31 patients with angiography had coronary artery disease (stenosis > 50%). When fixed and reversible defects were considered as positive, the sensitivity was 50%, the specificity was 65%, the positive predictive value was 33% and the negative predictive value was 79%.

CONCLUSIONS

Myocardial perfusion defects can be observed in more than one third of medically treated patients with HC. Only a quarter of catheterized patients, even with chest pain, have associated coronary artery disease. The accuracy of SPET for the diagnosis of coronary artery disease in hypertrophic cardiomyopathy is low. Thus, the value of this technique is limited in these patients.

Simultaneous dipyridamole/maximal subjective exercise with 99mTc-MIBI SPECT: improved diagnostic yield in coronary artery disease

OBJECTIVES

We attempted to demonstrate that simultaneous dipyridamole administration and maximal subjective exercise in patients who are unable to achieve a good exercise level can improve the diagnostic efficacy of technetium-99m methoxy isobutyl isonitrile (99mTc-MIBI) myocardial single-photon emission computed tomography (SPECT).

BACKGROUND

The results of myocardial perfusion scintigraphy are unsatisfactory if the level of exercise achieved by the patient is insufficient. The use of dipyridamole with maximal subjective stress testing has been shown to improve the quality of the thallium-201 myocardial perfusion images, but there are no studies demonstrating that this combination improves the diagnostic accuracy of myocardial perfusion SPECT.

METHODS

Two hundred thirty-one consecutive patients, without a previous myocardial infarction, were classified into three groups: group 1, 91 patients with an adequate exercise test; group 2, 68 patients with an inadequate exercise test; group 3, 72 patients with an inadequate exercise test who then received intravenous dipyridamole (0.56 mg/kg body weight over 4 min) simultaneously with exercise.

RESULTS

Results for sensitivity (89%) and negative predictive value (83%) in group 3 were significantly better than those in group 2 (71% [p = 0.03] and 56% [p = 0.002], respectively) and not significantly different from those in group 1. The polar maps of 20 patients studied with an without dipyridamole at the same exercise level revealed a significantly greater extent of ischemia in each territory and in a global assessment (19 + 20% vs. 8 + 11%, p < 0.0001) when dipyridamole was administered during physical exercise.

CONCLUSIONS

Intravenous dipyridamole administration during exercise testing is advisable in all patients who are unable to achieve an adequate exercise level. This approach permits physicians to avoid missing ergometric information while optimizing myocardial SPECT results.

[ST segment elevation during exercise test and perfusion scintigraphy in patients without infarction]

BACKGROUND

The features of perfusion scintigraphy in patients who show exercise-induced ST-segment elevation in the absence of previous infarction have been assessed in only a few reports. Therefore, we have evaluated our experience in a wide review of exercise 201-thallium scintigraphies.

METHODS

16,620 exercise 201-thallium scintigraphies, carried out between 1986 and 1993, have been retrospectively reviewed. Fourteen patients (0.8/1000) without previous infarction who were evaluated for chest pain showed ST-segment elevation. In all patients coronary arteriography was also available.

RESULTS

Five patients were free from significant coronary artery stenoses, 6 had one-vessel disease, 2 had two-vessel disease, and the remaining patient had three-vessel disease. In 8 patients ST-segment elevation (up to 3-24 mm) was inferior, in 5 anterior and in 1 lateral. The radionuclide was injected during ST-segment elevation in 10 cases and before such elevation (which developed in the postexercise phase) in 4. In 3 out of these 4, which had angiographically normal coronary arteries, the scintigraphy was negative. In all cases where thallium-201 was injected during ST elevation, severe perfusion defects were detected corresponding to the localization of ST elevation. In the 4 patients with critical coronary stenoses, thallium-201 redistribution after 3 hours was partial.

CONCLUSIONS

In patients without previous infarction and with exercise-induced ST-segment elevation, very severe perfusion defects are detected when the radionuclide has been injected during the crisis. Thallium-201 redistribution after 3 hours was not total in patients with fixed critical stenoses. When radionuclide injection preceded the crisis, the result of the scintigraphy was in agreement with the coronary anatomy.

[Diagnosis of coronary disease by means of stress gamma-tomography with 99m-technetium-isonitriles]

BACKGROUND

To assess the yield of exercise myocardial stress tomogammagraphy (SPET) with methoxy-isobutyl-isonitrile-technetium-99m (99mTc-MIBI) in the diagnosis of coronary artery disease.

METHODS

Seventy-two consecutive patients, without previous myocardial infarction and with coronary angiography, were investigated. All underwent a symptom-limited exercise test with intravenous infection of 15 mCi of 99mTc-MIBI 30-60 seconds before the end of exercise. Detection of tomographic images was performed after one hour. Rest images were detected 24 hours later. Images with exercise perfusion defects which became normal at rest were considered as positive.

RESULTS

Sensitivity (84%), specificity (93%), global value (87%), positive predictive value (95%), and negative predictive value (79%) of 99mTc-MIBI were significantly higher than those of conventional exercise electrocardiogram (46%, 69%, 55%, 69% and 46%, respectively). These values were lower when exercise test was insufficient (peak heart rate below 80% in the absence of angina). The sensitivity values were similar for the diagnosis of one (81%), two (76%), and three (93%) vessel disease. The application of Bayes' theorem disclosed that the highest yield of MIBI was achieved with prevalences ranging between 30% and 70%.

CONCLUSION

The efficacy of 99mTc-MIBI SPET for the diagnosis of coronary artery disease was satisfactory, particularly when exercise was sufficient and with a prevalence of coronary artery disease ranging between 30% and 70%.

[The usefulness of adenosine triphosphate in supraventricular paroxysmal tachycardias]

With the objective to evaluate adenosine triphosphate (ATP) usefulness in supraventricular paroxysmal tachycardia (SPT), doses of 0.25 mg/kg, of ATP are administered fastly i.v. in bolus, to fifty consecutive patients with SPT resistant to vagal stimulation maneuvers. The effect achieved allowed to identify two groups: a) 39 patients in whom tachycardia was interrupted; b) 11 patients in whom tachycardia did not cease, but the induced transient provoked atrial-ventricular (A-V) blockage allowed to identify the underlying mechanism of tachycardia (in 6 of them atrial tachycardia and in 5 atrial flutter). In both groups the ATP effect was present in less than 30 seconds. In seven patients (five from group (a) and two from group b) the QRS duration was over 0.12 s. Six patients had a left ventricular ejection fraction below 30%. Side effects were frequent, but always short. ATP could become the drug of choice in the treatment of SPT without response to vagal maneuvers, due to the fact that, to its therapeutic activity, it must be added its diagnostic usefulness, its fast action and metabolization, together with the fact that it does not induce severe side effects.

Lateral saccadic latencies and handedness

Lateral saccadic latencies were determined in 18 right-handers and 18 left-handers. Within the right-handed group the mean latency was significantly shorter when looking from the left to the right (242.7 msec) than from right to left (265.0 msec), whereas no significant directional difference was found in the left-handed group. An age effect was also found with longer latencies being associated with increased age. These findings agree with those of Pirozzolo and Rayner (Neuropsychologia 18, 225-229, 1980) and provide further evidence of the pervasiveness of functional asymmetry in the human brain. The present findings suggest that motoric or central integrative mechanisms may contribute more to saccadic directional asymmetries than do perceptual differences.

Diminished reaction to a novel stimulus during amphetamine withdrawal in rats

This experiment determined whether reaction to a novel stimulus was diminished in a dose-dependent fashion following 8 consecutive days of d-amphetamine administration. Thirty-two male rats were injected with saline, 0.5, 2.5, or 5.0 mg/kg of d-amphetamine (each N = 8). On the ninth day, all animals received saline injections and were tested (a) in the presence of a novel stimulus, or (b) in the absence of a novel stimulus. Reaction to the novel stimulus varied inversely with the dose of d-amphetamine which had been received during the drug administration period. This reduction in reaction to the novel stimulus did not seem to depend on (a) the level of amphetamine-induced sterotypy at the end of the drug administration period (b) general reduction of activity, or (c) interference by drug-conditioned responses.