Frailty assessment using photographs in patients undergoing transcatheter aortic valve replacement.

BACKGROUND: When frailty is considered in patient selection, better outcomes are achieved in transcatheter aortic valve replacement (TAVR) procedures. This study investigated whether patient photographs could be utilized to qualitatively assess patient frailty and independently predict poor outcomes following TAVR. METHODS: This study included 1345 patients with severe aortic stenosis who underwent TAVR at the Sakakibara Heart Institute, Japan, between 2013 and 2022. Patient photographs were taken prior to the initial outpatient clinic examination or at discharge in case the patient's first visit was unplanned admission. Frailty was assessed from patient photographs using a four-point photographic frailty scale; 1 (non-frail), 2 (vulnerable), 3 (mild frail), and 4 (frail). Photographic frailty scale of 3 and 4 were defined as high. The primary endpoint was all-cause mortality following TAVR. RESULTS: Seven hundred ninety-six patients who had their facial photographs taken within six months before the TAVR procedure were analyzed. Patients with a higher photographic frailty scale belonged to New York Heart Association classes III/IV, and had higher Society of Thoracic Surgeons scores, higher incidence of wheelchair usage, lower hemoglobin, and smaller aortic valve areas. According to the frailty assessment, patients with a higher photographic frailty scale exhibited slower performance in the 5-m walk test, reduced hand grip strength, more severe dementia, had a higher clinical frailty scale, and lower serum albumin level. Multivariable Cox regression analysis revealed that the high photographic frailty scale was independently associated with all-cause mortality (adjusted hazard ratio 1.62, 95 % confidence interval 1.12-2.33, p = 0.010). Kaplan-Meier analysis indicated that patients with high photographic frailty scale had higher all-cause mortality rates compared to those with low scale (log-rank p = 0.011). CONCLUSIONS: Patient registration photographs can be used to obtain qualitative assessments of frailty in severe aortic stenosis cases, and such assessments can independently predict poor outcomes following TAVR.

Exploring the Frailty Components Related to Hospitalization-Associated Disability in Older Patients After Cardiac Surgery Using a Comprehensive Frailty Assessment.

BACKGROUND: We investigated the components of frailty associated with hospitalization-associated disability (HAD) after cardiac surgery.Methods and Results: This retrospective, observational study evaluated 1,446 older patients after elective cardiac surgery at the Sakakibara Heart Institute. We examined the association between HAD and 7 domains of frailty assessed by the Kihon Checklist. HAD was defined as a decline in the ability to perform activities of daily living (ADL) between admission and discharge, as assessed by the Barthel Index. Logistic regression and decision tree analysis were used to identify associations between the number and type of frailty components and HAD. Of the 1,446 patients, 190 were excluded, and 90 (7%) developed HAD. An increase in the number of frailty components was a risk factor for HAD (odds ratio: 1.88, 95% confidence interval: 1.62-2.17). Decision tree analysis identified physical functional decline, depression, and cognitive dysfunction as factors associated with HAD. The incidence of HAD was highest in cases of physical functional decline (21%) and lowest for cases in which the 3 aforementioned factors were absent (2.8%). CONCLUSIONS: An increased number of frailty factors increased the risk of HAD and the findings also reaffirmed the importance of a comprehensive assessment to evaluate the risk of HAD, including evaluation of physical function, cognitive function, and depression.

Current Medical and Social Issues for Hospitalized Heart Failure Patients in Japan and Factors for Improving Their Outcomes　- Insights From the REAL-HF Registry.

Background: We investigated the current medical and social conditions and outcomes of heart failure (HF) patients in Hiroshima Prefecture, a local district in Japan. Methods and Results: From March 2017 to February 2018 we enrolled all adult patients with hospitalized HF in 8 regional core hospitals that provided an interprofessional team approach for HF patients. We collected patients' clinical characteristics and information regarding living circumstances, cognitive function, quality of life, and interprofessional team approach. For patients discharged home, we followed up the primary endpoint (all-cause death and all-cause unscheduled readmission), conditions of outpatient cardiac rehabilitation, and home nursing-care services over a 1-year period after discharge. Of the registered patients (n=1,218), 39.2% were super-elderly (≥85 years old); more than half of these patients had preserved ejection fraction (≥50%). In the follow-up cohort (n=632), 140 patients (22.2%) were readmitted with HF exacerbation as the primary endpoint, and almost half (n=295, 46.7%) experienced any primary endpoint. The multivariate analysis adjusted for medical and social factors showed that completion of outpatient cardiac rehabilitation (5-month program) remained a strong negative predictor of the primary endpoint (hazard ratio: 0.15; 95% confidence interval: 0.05-0.48; P=0.0013). Conclusions: Our cohort study highlighted the super-aging of current HF patients in Japan. Cardiac rehabilitation through continuous team approach appears to be associated with favorable overall outcomes in this population.

Nationwide Actions Against Heart Failure Pandemic in Japan　- What Should We Do From Academia?

Heart failure pandemic is rapidly approaching in Japan, requiring nationwide actions. In particular, the Japanese Circulation Society and related societies launched the Stroke and Cardiovascular Disease Control Act, which was passed by the National Diet, as the first ever legislative policy measure against stroke and cardiovascular disease. In association with this, actions against heart failure pandemic from the scientific field are also important. Because heart failure pandemic is a critical problem not only in Japan but also in many developed countries, we believe the nationwide approach, as summarized here, will greatly contribute to the development of cardiovascular medicine, particularly the management and treatment of heart failure worldwide.

Cognitive assessment using the revised Hasegawa's dementia scale to determine the mid-term outcomes following transcatheter aortic valve replacement.

BACKGROUND: Several predictors are available to guide patient selection for transcatheter aortic valve replacement (TAVR) to achieve better outcomes, and cognitive function is one of these predictors. This study investigated whether the revised Hasegawa's dementia scale (HDS-R) could independently predict mid-term outcomes following TAVR. METHODS: The study population comprised 455 patients with severe aortic stenosis who underwent TAVR at the Sakakibara Heart Institute between 2010 and 2018. The primary endpoint was all-cause mortality following TAVR. Patients were dichotomized into two groups according to the receiver operating characteristic analysis (HDS-R ≤23 and >23). RESULTS: Patients with HDS-R ≤23 were older, were more frail, were more likely to have peripheral artery disease, had lower serum albumin levels, had lower ejection fractions, and had smaller aortic valve areas than those with HDS-R >23. By definition, 81 of the 455 patients (17.8%) were considered to have dementia (HDS-R ≤20) before TAVR. The discriminatory performance for predicting all-cause mortality at 3 years was greater for dichotomization with 23/24 than that with 20/21 [area under the curve (AUC): 0.63, 95% confidence interval (CI): 0.50-0.76, p=0.047 vs. AUC: 0.52, 95% CI: 0.39-0.65, p=0.713]. From the Kaplan-Meier analysis, patients with HDS-R ≤23 had higher mortality rates than those with HDS-R >23 (86.8±3.3% and 75.4±4.7% at 3 years, respectively; log-rank p=0.001). The multivariate Cox regression analysis found that the HDS-R was independently associated with all-cause mortality (hazard ratio 2.11, 95% CI 1.21-3.69, p=0.008). CONCLUSIONS: Patients with HDS-R ≤23 were sicker and more frail and had greater cognitive impairment. Additionally, HDS-R could independently predict mid-term outcomes following TAVR.

Superiority of novel automated assessment of aortic annulus by intraoperative three-dimensional transesophageal echocardiography in patients with severe aortic stenosis: Comparison with conventional cross-sectional assessment.

BACKGROUND: Previous studies have demonstrated that three-dimensional (3D) transesophageal echocardiography (TEE) is an alternative to multi-detector computed tomography (MDCT) for aortic valve sizing in transcatheter aortic valve replacement (TAVR). However, conventional cross-sectional analysis of aortic annulus by 3D TEE has some limitations such as lengthy analytical time. A novel software for automated valve measurement has been developed for 3D TEE. We evaluated the accuracy and analytical time of aortic annular measurements using this novel automated software in the clinical setting. METHODS: We retrospectively studied 43 patients with symptomatic severe aortic stenosis (AS) who underwent TAVR. All patients underwent intraoperative TEE and MDCT. We measured aortic annular area by automated, semi-automated, and cross-sectional methods using 3D TEE datasets. These measurements were compared to the corresponding MDCT reference values. We also compared the analytical time of the three methods. RESULTS: Automated and semi-automated analyses required significantly shorter analytical time compared to cross-sectional analysis (automated: 30.1±5.79s, semi-automated: 74.1±15.0s, manual: 81.8±18.5s, p<0.05). Compared to MDCT measurement (393.7±81.0mm2), annular areas measured by automated and cross-sectional methods were significantly smaller (automated: 380.6±77.1mm2, cross-sectional: 374.7±76.8mm2, p<0.05), while that obtained by semi-automated method was not significantly different (387.7±75.8mm2). Annular areas determined by semi-automated and cross-sectional analyses had narrower limits of agreement (LOA) with MDCT measurements, compared to automated analysis (automated: -68.6 to 94.7mm2, semi-automated: -48.3 to 60.2mm2, cross-sectional: -40.0 to 77.9mm2). Measurements by all three methods using 3D TEE showed high correlation with MDCT measurement (automated: r=0.86, semi-automated: r=0.94, cross-sectional: r=0.93). CONCLUSIONS: For aortic annular measurements using 3D TEE in AS patients, semi-automated analysis using the novel automated software reduced analytical time while maintaining similar accuracy compared to the conventional cross-sectional analysis. This automated software may have acceptable feasibility in the clinical setting.

Coronary physiological assessment combining fractional flow reserve and index of microcirculatory resistance in patients undergoing elective percutaneous coronary intervention with grey zone fractional flow reserve.

OBJECTIVES: The aim of this study is to investigate the association between fractional flow reserve (FFR) values and change in coronary physiological indices after elective percutaneous coronary intervention (PCI). BACKGROUND: Decision making for revascularization when FFR is 0.75-0.80 is controversial. METHODS: A retrospective analysis was performed of 296 patients with stable angina pectoris who underwent physiological examinations before and after PCI. To investigate the differences of coronary flow improvement between territories with low-FFR (<0.75) and grey-zone FFR (0.75-0.80), serial changes in physiological indices including mean transit time (Tmn), coronary flow reserve (CFR), and index of microcirculatory resistance (IMR) were compared between these two groups. RESULTS: Compared to low-FFR territories, grey-zone FFR territories showed significantly lower prevalence of Tmn shortening, CFR improvement, and decrease in IMR (Tmn shorting, 63.9% vs. 87.0%, P < .001; CFR improvement, 63.0% vs. 75.7%, P = .019; IMR decrease, 51.3% vs. 63.3%, P = .040) and lower extent of their absolute changes (Tmn shorting, 0.06 (-0.03 to 0.16) vs. 0.22 (0.07-0.45), P < .001; CFR improvement, 0.45 (-0.32 to 1.87) vs. 1.08 (0.02-2.44), P < .01; IMR decrease, 0.2 (-44.0 to 31.3) vs. 2.9 (-2.9 to 11.8), P = .022). Multivariate analysis showed that pre-PCI IMR predicted improved coronary flow profile in both groups, whereas pre-PCI FFR predicted increased coronary flow indices in low-FFR territories. CONCLUSIONS: Worsening of physiological indices after PCI was not uncommon in territories showing grey-zone FFR. Physiological assessment combining FFR and IMR may help identify patients who may benefit by PCI, particularly those in the grey zone.

Optical coherence tomography assessment of newgeneration mesh-covered stents after carotid stenting.

AIMS: The aim of this study was to identify the findings (by optical coherence tomography [OCT]) after carotid artery stenting (CAS) with two different types of new-generation mesh-covered stent. METHODS AND RESULTS: Sixteen consecutive patients undergoing CAS with mesh-covered stents and highdefinition OCT image acquisition were enrolled in the study. Cross-sectional OCT images for the presence of strut malapposition (SM) and plaque prolapse (PP) were evaluated using a proximal or distal embolic protection device (EPD). CGuard stents were used in 11 patients (68.8%) and RoadSaver stents in five (31.2%). With OCT analysis, the incidence of SM was 20.5% for CGuard vs. 26.8% for RoadSaver, p=0.26, and the incidence of PP was 10.8% for CGuard vs. 20.7% for RoadSaver, p=0.05. No neurological complications (stroke/TIA) occurred during the procedural and post-procedural periods. CONCLUSIONS: The OCT findings of two different types of mesh-covered stent after CAS were obtained safely. Our work indicates that current mesh-covered carotid stents may show differences in SM and PP. The effect of stent design and implantation technique on OCT findings post CAS, and their relation to longterm clinical outcomes, require further evaluation.

Assessment of vascular autonomic function using peripheral arterial tonometry.

Peripheral autonomic function is impaired in diabetic polyneuropathy. However, it is difficult to evaluate it due to the lack of non-invasive quantitative assessment. We aimed to establish a novel index to evaluate vascular autonomic function using reactive hyperemia peripheral arterial tonometry (RH-PAT), a widely performed endothelial function test. Sixty-five subjects were enrolled, including healthy subjects, cases with sympathetic nerve blockers, and diabetic patients. RH-PAT was performed with 5-min blood flow occlusion in unilateral arm. We calculated the reduction ratio of the post-occlusion pulse amplitude to the baseline in the non-occluded arm (RPN), with 1-min sliding window. In healthy subjects, RPN gradually increased with time-dependent manner. However, this phenomenon was eliminated in cases with sympathetic nerve blockers. Plasma concentration of norepinephrine was measured before and after the blood flow occlusion, which showed a significant increase. We then compared RPNs with the change in heart rate variability (HRV) parameters. RPN calculated at 5 min after the reperfusion had the highest correlation with the change in sympathetic HRV parameter, and thus, we named sympathetic hypoemia index (SHI). Finally, we studied the relationship between SHI and diabetes. SHI was significantly lower in diabetic patients than matched controls. SHI, a novel index derived from RH-PAT, represented the peripheral sympathetic activity. SHI may be useful for assessing the vascular autonomic activity in diabetic patients.

The influence of elective percutaneous coronary intervention on microvascular resistance: a serial assessment using the index of microcirculatory resistance.

This study investigates whether hyperemic microvascular resistance (MR) is influenced by elective percutaneous coronary intervention (PCI) by using the index of microcirculatory resistance (IMR). Seventy-one consecutive patients with stable angina pectoris undergoing elective PCI were prospectively studied. The IMR was measured before and after PCI and at the 10-mo follow-up. The IMR significantly decreased until follow-up; the pre-PCI, post-PCI, and follow-up IMRs had a median of 19.8 (interquartile range, 14.6-28.9), 16.2 (11.8-22.1), and 14.8 (11.8-18.7), respectively (P < 0.001). The pre-PCI IMR was significantly correlated with the change in IMR between pre- and post-PCI (r = 0.84, P < 0.001) and between pre-PCI and follow-up (r = 0.93, P < 0.001). Pre-PCI IMR values were significantly higher in territories with decreases in IMR than in those with increases in IMR [pre-PCI IMR: 25.4 (18.4-35.5) vs. 12.5 (9.4-16.8), P < 0.001]. At follow-up, IMR values in territories showing decreases in IMR were significantly lower than those with increases in IMR [IMR at follow-up: 13.9 (10.9-17.6) vs. 16.6 (14.0-21.4), P = 0.013]. The IMR decrease was significantly associated with a greater shortening of mean transit time, indicating increases in coronary flow (P < 0.001). The optimal cut-off values of pre-PCI IMR to predict a decrease in IMR after PCI and at follow-up were 16.8 and 17.0, respectively. In conclusion, elective PCI affected hyperemic MR and its change was associated with pre-PCI MR, resulting in showing a wide distribution. Overall hyperemic MR significantly decreased until follow-up. The modified hyperemic MR introduced by PCI may affect post-PCI coronary flow.

Quantitative assessment of tissue prolapse on optical coherence tomography and its relation to underlying plaque morphologies and clinical outcome in patients with elective stent implantation.

BACKGROUND: Tissue prolapse (TP) is sometimes observed after percutaneous coronary intervention (PCI), but its clinical significance remains unclear. We investigated the relationship between TP volume on optical coherence tomography (OCT) after PCI and underlying plaque morphologies and the impact of TP on clinical outcomes. METHODS: We investigated 178 native coronary lesions with normal pre-PCI creatine kinase-myocardial band (CK-MB) values (154 lesions with stable angina; 24 with unstable angina). TP was defined as tissue extrusion from stent struts throughout the stented segments. All lesions were divided into tertiles according to TP volume. The differences in plaque morphologies and 9-month clinical outcomes were evaluated. RESULTS: TP volume was correlated with lipid arc (r=0.374, p<0.0001) and fibrous cap thickness (r=-0.254, p=0.001) at the culprit sites. The frequency of thin-cap fibroatheroma (TCFA) was higher in the largest TP tertile (≥ 1.38 mm(3)) (p=0.015). In multivariate analysis, right coronary artery lesion (odds ratio [OR]: 2.779; p=0.005), lesion length (OR: 1.047; p=0.003), and TCFA (OR: 2.430; p=0.022) were related to the largest TP tertile. Lesions with post-PCI CK-MB elevation (>upper reference limit) had larger TP volume than those without (1.28 [0.48 to 3.97] vs. 0.70 [0.16 to 1.64] mm(3), p=0.007). The prevalence of cardiac events during the 9-month follow-up was not significantly different according to TP volume. CONCLUSIONS: TP volume on OCT was related to plaque morphologies and instability, and post-PCI myocardial injury, but not to worse 9-month outcomes.

Diagnosis and assessment of Takayasu arteritis by multiple biomarkers.

BACKGROUND: Patients with Takayasu arteritis (TA) often show recurrence under steroid treatment without an elevation of C-reactive protein (CRP). There is a report that matrix metalloproteinase (MMP)-2, MMP-3, MMP-9 and pentraxin3 (PTX3) could be sensitive biomarkers, but the characteristics of these biomarkers have not been established. METHODS AND RESULTS: We enrolled 45 consecutive patients; 28 were grouped in an active phase as evidenced by clinical recurrence within 2 years of blood sampling. Circulating levels of high-sensitivity (hs)CRP, MMPs, and PTX3 were determined. Patients in an active phase showed higher levels of hsCRP, MMP-9, and PTX3. Area under the receiving operating characteristics curves of hsCRP and PTX3 were significantly higher than that of MMP-9. Among the 28 patients with active TA, 71% was positive for hsCRP and 82% for PTX3. Patients without recurrence showed significantly higher plasma levels of MMP-9. There was a positive correlation between the plasma MMP-3 level and the prednisolone dose. However, PTX3 and MMP-9 levels did not have such a correlation. CONCLUSIONS: PTX3 and MMP-9, which are not affected by prednisolone, could be sensitive biomarkers for assessing TA activity. Evaluation of MMP-9 may suggest prior existence of TA.

Assessment of echo-attenuated plaque by optical coherence tomography and its impact on post-procedural creatine kinase-myocardial band elevation in elective stent implantation.

OBJECTIVES: This study examined morphological characteristics of echo-attenuated plaques by optical coherence tomography (OCT) and evaluated their influence on creatine kinase-myocardial band (CK-MB) elevation after percutaneous coronary intervention (PCI) in patients with elective stent implantation. BACKGROUND: Recent intravascular ultrasound studies have described atherosclerotic plaques with echo attenuation (EA) without associated bright echoes that are correlated with no-reflow phenomenon after PCI. METHODS: We studied 135 native de novo culprit coronary lesions in 135 patients with normal pre-PCI CK-MB levels (28 with unstable angina; 107 with stable angina) who underwent intravascular ultrasound and OCT examinations before elective stent implantation. The lesions were divided into 2 groups based on the presence or absence of EA, and OCT findings were compared. We then determined predictors of post-PCI CK-MB elevation. RESULTS: EA was found in 47 (34.8%) lesions and was associated with the presence of OCT-derived thin-capped fibroatheroma, ruptured plaques, greater lipid content, intravascular ultrasound-derived large reference and plaque area, lesion eccentricity, and microcalcification. Elevated CK-MB levels were observed in 36 (26.7%) lesions, and significantly more frequently in lesions with EA than without. In multivariable analysis, EA (odds ratio [OR]: 3.49; 95% confidence interval [CI]: 1.53 to 7.93; p = 0.003) and OCT-derived ruptured plaque (OR: 2.92; 95% CI: 1.21 to 7.06; p = 0.017) were independent predictors of post-PCI CK-MB elevation. CONCLUSIONS: Atherosclerotic plaques with EA were associated with characteristics considered to be high risk or unstable. OCT examination showed an additive predictive value to the presence of EA for post-PCI CK-MB elevation.

Assessment of acute injuries and chronic intimal thickening of the radial artery after transradial coronary intervention by optical coherence tomography.

AIMS: Transradial coronary intervention (TRI) introduces a trauma to the radial artery (RA), possibly influencing quality as a bypass conduit if subsequently used. We sought to determine the acute and chronic effects of TRI on the RA by optical coherence tomography (OCT). METHODS AND RESULTS: Immediately after TRI completion, 73 RAs in 69 patients were examined. The sheath was pulled back 2 cm distal to the puncture site, and OCT imaging was performed. The acute injuries and intimal thickening were compared between first-TRI RAs and repeat-TRI RAs. Intimal tears were observed in 49 RAs (67.1%) and were more frequent in the distal than in the proximal RA (P = 0.001). Medial dissections were not uncommon (26 RAs, 35.6%). The frequency of acute injury was significantly higher in repeat-TRI RAs (P < 0.001). Intima/medial area, the maximum intimal thickness/medial thickness ratio, and per cent narrowing were all significantly greater in repeat-TRI RAs in the distal and proximal RA. Multivariate analysis revealed that a repeated TRI procedure was the only independent predictor of intimal thickening. CONCLUSION: Optical coherence tomography clearly demonstrated significant acute injuries and chronic intimal thickening of RA after TRI. Further study should evaluate the impact of these effects when TRI RAs are subsequently used as conduits, on long-term graft patency and on clinical outcomes after bypass surgery.

Early validation study of 64-slice multidetector computed tomography for the assessment of myocardial viability and the prediction of left ventricular remodelling after acute myocardial infarction.

AIMS: We aim to validate the ability of multidetector computed tomography (MDCT) for assessing myocardial viability and predicting left ventricular (LV) remodelling after acute myocardial infarction (AMI). METHODS AND RESULTS: In 52 consecutive patients with first AMI, 64-slice MDCT without iodine re-injection was performed immediately following coronary stenting. Electrocardiogram-gated thallium-201 single-photon emission tomography was performed using QGS programs within 5 days and 6 months after onset. Among the 52 patients, 18 patients (Group A) showed transmural contrast-delayed enhancement on MDCT images, 20 patients (Group B) showed subendocardial contrast-delayed enhancement, and 14 patients (Group C) had no contrast-delayed enhancement. In the acute phase, peak creatine kinase-MB [497 (189-744), 182 (90-358), 85 (40-204) IU/mL, respectively, P = 0.0004] was significantly higher in Group A, while the incidence of myocardial blush grade 3 (22, 67, 75%, respectively, P = 0.001) and LV ejection fraction (41 +/- 7, 53 +/- 12, 62 +/- 11%, respectively, P < 0.0001) were significantly lower in Group A. During the 6-month period, LV remodelling (P = 0.001) and the number of rehospitalization for heart failure (P = 0.0017) were more significantly observed in Group A. CONCLUSION: Myocardial contrast-delayed enhancement patterns provide promising information regarding myocardial viability, LV remodelling, and prognosis in AMI.

Clinical assessment of antiarrhythmic agents for paroxysmal atrial fibrillation guided by modification of electrophysiologic arrhythmogenicity.

INTRODUCTION: Rapid atrial pacing alters atrial electrophysiology, promoting initiation and maintenance of atrial fibrillation (AF). The aim of this study was to assess differences in the electrophysiologic properties of atrial tissue between patients with and without AF episodes and to determine whether electrophysiologic properties can predict the clinical efficacy of antiarrhythmic agents. METHODS AND RESULTS: Sixty patients were studied, 33 with documented episodes of paroxysmal atrial fibrillation (PAF) and 27 control patients. Atrial effective refractory period (AERP), atrial vulnerability, and intra-atrial conduction time were measured at baseline and after rapid constant atrial pacing for 5 minutes at rates of 130, 150, 170, and 190 beats/min. The clinical efficacy of antiarrhythmic agents for PAF prophylaxis was assessed over 14 months with an antiarrhythmic agent identical to that administered intravenously, and the antiarrhythmic agent effects on AERP, atrial vulnerability, and intra-atrial conduction time were assessed. AERP shortening and atrial vulnerability increase were significantly larger in the PAF group. Antiarrhythmic agents that were clinically effective in suppressing PAF significantly attenuated AERP shortening, but antiarrhythmic agents that were clinically ineffective did not. CONCLUSION: Changes in AERP and atrial vulnerability observed after rapid atrial pacing are considered indicative of the electrophysiologic substrate of PAF. Attenuation of AERP and atrial vulnerability by antiarrhythmic agents might be useful in predicting their clinical efficacy.

Transvenous catheter cryoablation of the atrioventricular node and visual assessment of freezing of cardiac tissue using intracardiac echocardiography.

We investigated the use of a catheter-based cryoablation system on atrioventricular (AV) junction ablation in dogs. In five dogs, the cryoablation catheter was introduced to the AV junction area in order to create transient high degree or complete AV block. Cryo-freezing energy was applied by lowering the temperature to -75 degrees C for five minutes as a single cycle. This cycle was repeated until significant impairment of the AV conduction appeared. Transient high degree and complete AV block was obtained in all five dogs without any adverse effects. The iceball formation was identified by intracardiac echocardiography. Ablation of the AV junction is effective with several freeze-thaw cycles using a transvenous catheter cryoablation system.