Hideomi Fujiwara

Electrical Connections Between Pulmonary Veins

Background— Electrical disconnection of the myocardial extensions into arrhythmogenic pulmonary veins (PVs) is recognized as a curative technique for paroxysmal atrial fibrillation (AF). However, the presence of electrical connections between the PVs, which may make achievement of PV disconnection difficult, has not been systematically evaluated. Methods and Results— Forty-nine consecutive patients with drug-resistant AF underwent ostial radiofrequency (RF) catheter ablation of arrhythmogenic PVs with foci triggering AF. Pacing from inside the targeted PV was performed after each RF delivery to identify the left atrial exit site of the residual venoatrial conduction. Successful PV disconnection was defined as achieving elimination of the PV potentials during sinus rhythm or left atrial pacing, and the loss of left atrial conduction during intra-PV pacing. A total of 112 arrhythmogenic PVs were identified. PV disconnection was achieved with 10±6.1 minutes of RF delivery to the ostia of 101 targeted PVs. In...

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.

In vivo critical fibrous cap thickness for rupture-prone coronary plaques assessed by optical coherence tomography

AIMS The widely accepted threshold of <65 μm for coronary plaque fibrous cap thickness was derived from postmortem studies of ruptured plaques and may not be appropriate for in vivo rupture-prone plaques. We investigated the relationship between fibrous cap thickness and plaque rupture using optical coherence tomography (OCT). METHODS AND RESULTS We studied 266 lesions (103 from patients with acute coronary syndrome and 163 from patients with stable angina) before percutaneous coronary intervention using OCT. Ruptured and non-ruptured lipid-rich plaques were identified and the thinnest and most representative fibrous cap thickness were determined. Cap thickness was reliably measured in 71 ruptured and 111 non-ruptured plaques. From the ruptured plaques, the median thinnest cap thickness was 54 μm (50-60). The median most representative cap thickness was 116 μm (103-136). For non-ruptured plaques, the median thinnest cap thickness was 80 μm (67-104) and 182 μm (156-216) for most representative cap thickness. In 95% of ruptured plaques, the thinnest cap thickness and most representative cap thickness were <80 and <188 μm, respectively. The best cut-offs for predicting rupture were <67 μm (OR: 16.1, CI: 7.5-34.4, P < 0.001) for the thinnest cap thickness and <151 μm (OR: 35.6, CI: 15.0-84.3, P < 0.001) for most representative cap thickness. These two measures were modestly correlated (r(2) = 0.39) and both independently associated with rupture. CONCLUSION In vivo critical cap thicknesses were <80 μm for the thinnest and <188 μm for most representative fibrous cap thickness. Prospective imaging studies are required to establish the significance of these values.

Impact of Coronary Plaque Morphology Assessed by Optical Coherence Tomography on Cardiac Troponin Elevation in Patients With Elective Stent Implantation

Background—Mild elevations of cardiac troponin frequently occur after percutaneous coronary intervention (PCI), and patients with elevated post-PCI biomarkers have a worse prognosis. We used optical coherence tomography (OCT) to study the relationship between pre-PCI plaque morphology and post-PCI cardiac troponin I elevations. Methods and Results—One hundred thirty-one patients with normal pre-PCI cardiac troponin I levels underwent OCT before nonemergency stent implantation. Clinical and OCT findings were compared between patients with (n=31, 23.7%) and without (n=100, 76.3%) post-PCI cardiac troponin I of >3×upper reference limit (post-PCI myocardial infarction [MI]). After PCI, long-term follow-up data were collected. Post-PCI MI was associated with angiographic lesion length, type B2/C lesions, presence of thin-cap fibroatheroma, and fibrous cap thickness. In multivariable analysis, presence of thin-cap fibroatheroma (odds ratio, 10.47; 95% confidence interval, 3.74 to 29.28; P<0.001) and type B2/C lesions (odds ratio, 3.74; 95% confidence interval, 1.41 to 9.92; P=0.008) were predictors of post-PCI MI. At a median follow-up of 12 months, cardiac event-free survival was significantly worse in patients with post-PCI MI (log-rank test &khgr;2=8.9; P=0.003). Cox proportional hazards analysis showed that post-PCI MI (hazard ratio, 3.67; 95% confidence interval, 1.39 to 9.65; P=0.009) and ejection fraction (hazard ratio, 0.96; 95% confidence interval, 0.92 to 0.99; P=0.029) were independent predictors of adverse cardiovascular events during follow-up. Conclusions—Type B2/C lesions and the presence of OCT-defined thin-cap fibroatheroma can predict post-PCI MI in patients treated with elective stent implantation, who may require adjunctive therapy after otherwise successful PCI.

Prognostic significance of sustained monomorphic ventricular tachycardia induced by programmed ventricular stimulation using up to triple extrastimuli in survivors of acute myocardial infarction

The prognostic significance of sustained monomorphic ventricular tachycardia (VT) induced by programmed ventricular stimulation using up to 3 extrastimuli was evaluated in 133 consecutive survivors of acute myocardial infarction (AMI) at a mean interval of 1.8 +/- 1.1 months after onset. This was compared with hemodynamic and angiographic abnormalities shown by cardiac catheterization and ventricular ectopic activity detected by Holter monitoring. Sustained monomorphic VT was induced in 25 (19%) patients, sustained polymorphic VT in 11 (8%) patients, nonsustained monomorphic VT (greater than or equal to 10 beats) in 12 patients (9%) and nonsustained polymorphic VT in 9 patients (7%). Multivariate logistic regression analysis of clinical, angiographic, hemodynamic and electrocardiographic variables showed that the presence of a left ventricular aneurysm (p = 0.005) and Lown grade 4B ventricular ectopic activity (p less than 0.001) were independent predictors of inducibility of sustained monomorphic VT. During a mean follow-up of 21 +/- 13 months, there were 8 (6%) sudden cardiac deaths and 3 (2.3%) spontaneous occurrences of life-threatening sustained VT. The 2-year probability of freedom from sudden cardiac death or sustained ventricular tachyarrhythmias was 53 +/- 13% for patients with inducible sustained monomorphic VT, 70 +/- 10% for those with a left ventricular ejection fraction less than 40% and 58 +/- 13% for those with Lown grade 4B ventricular ectopic activity.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Impact of plaque morphology on creatine kinase-MB elevation in patients with elective stent implantation

BACKGROUNDS The association between percutaneous coronary intervention (PCI) and subsequent myonecrosis has been widely recognized, and worse prognosis has been reported among patients with elevated post-PCI biomarkers. We used optical coherence tomography (OCT) to study the relationship between pre-PCI plaque morphology and post-PCI creatine kinase-MB (CK-MB) elevation. METHODS One hundred and twenty-five patients with normal pre-PCI CK-MB levels underwent OCT examination before nonemergency stent implantation. Patients were divided into two groups according to the presence (Group CK, n=35) or absence (Group NCK, n=90) of post-PCI CK-MB elevation ≥ upper limit of the normal range. Clinical and the OCT findings were compared between the two groups. RESULTS Elevated CK-MB levels was observed in 35 patients (28%). The CK-MB elevation was associated with elevated white blood cell count, type B2/C lesions, the presence of thin cap fibroatheroma (TCFA), plaque rupture, and lipid quadrants. In the multivariate analysis, the presence of TCFA (OR 4.68, 95% CI 1.88-11.64, p=0.001) and type B2/C lesions (OR 4.20, 95% CI 1.30-13.59, p=0.02) were independent predictors of post-PCI CK-MB elevation. CONCLUSIONS TCFA and angiographically complex lesion morphology can predict post-PCI CK-MB elevation in patients treated with elective stent implantation. OCT may be useful in stratifying the risk for nonemergency stent implantation.

Clinical Significance of Echo Signal Attenuation on Intravascular Ultrasound in Patients With Coronary Artery Disease

Background—Atherosclerotic plaque that shows echo signal attenuation (EA) without associated bright echoes is sometimes observed by intravascular ultrasound but its clinical significance remains unclear. We investigated the impact of EA on coronary perfusion and evaluated the pathological features of plaque with EA. Methods and Results—We studied 687 native coronary lesions in 687 consecutive patients (336 with acute coronary syndrome and 351 with stable angina pectoris) who underwent intravascular ultrasound before percutaneous coronary intervention. By subgroup analysis, 60 lesions (30 lesions with EA) treated with directional coronary atherectomy underwent pathological examination. The Thrombolysis in Myocardial Infarction (TIMI) flow grade and myocardial blush grade after percutaneous coronary intervention were compared between lesions with and without EA in 627 lesions except directional coronary atherectomy subgroup. EA was observed in 245 lesions (35.7%), and coronary flow after percutaneous coronary intervention was worse for lesions with EA than without (final TIMI grade of 0 to 2: 15.4% versus 2.4%, P<0.001; final myocardial blush grade of 0 to 2: 45.6% versus 21.4%, P<0.001). Multivariate analysis revealed a significant association between no reflow (TIMI grade 0 to 2) and EA (odds ratio, 5.59; 95% CI, 2.64 to 11.85; P<0.001), a baseline TIMI grade of 0 to 2 (odds ratio, 5.91; 95% CI, 2.79 to 12.5; P<0.001), and a large reference area (odds ratio, 3.08; 95% CI, 1.40 to 6.76; P=0.005) after controlling for other associated factors. Pathological examination revealed a significantly higher frequency of lipid-rich plaque with microcalcification in lesions with EA. Conclusions—Atherosclerotic plaque with EA showed a significant association with no reflow after percutaneous coronary intervention, suggesting the existence of fragile components susceptible to distal embolization.

High Energy Radiofrequency Catheter Ablation for Common Atrial Flutter Targeting the Isthmus between the Inferior Vena Cava and Tricuspid Valve Annulus Using a Super Long Tip Electrode

There have been controversies concerning the optimal target sites and approaches in radiofre‐quency catheter ablation of common atrial flutter. We attempted high energy radiofrequencv catheter ab‐lation targeting the isthmus between the inferior vena cava and tricuspid valve annulus (IVC‐TV isthmus) with a super long (8 mm) tip electrode, and compared the efficacy of this anatomical approach with the electrophysiological approach targeting the posteroseptal right atrium posterior to the coronary sinus us‐ing a standard 4‐mm tip electrode. Atrial flutter was successfully ablated in 12 of 12 patients (100%) with‐out recurrence with the anatomical approach, while, in 7 of 9 patients (64%) with 2 recurrences with the electrophysiological approach. In comparison of ablation data between the anatomical and electrophysi‐ological approaches, there were significant differences in the mean number of application pulses (anatomical vs electrophysiological: 2.3 ± 0.8 vs 9.9 ± 6.4, P < 0.01), applied wattage (39 ± 12Wvs24 ± 6W.P < 0.01), applied energy per application (1.986 ± 426 / vs 659 ± 323 J. P < O.O1), fluoroscopic time (26 ± 11 min vs 74 ± 30 minutes, P < 0.01), and procedure time (59 ± 8 min vs 181 ± 53 min. P < 0.01). In conclusion, the anatomical approach is superior to the electrophysiological one with respect to proce‐dure and radiation time, and linear ablation at the IVC‐TV isthmus with an 8‐wm tip electrode and high energy application is highly effective and safe.

Atrioventricular Nodal Physiology After Slow Pathway Ablation

The A V nodal physiology before and 1 week after “slow pathway potential” guided catheter ablation was examined in 32 patients with AV nodal reentrant tachycardia. A mean of 4.9 applications of radiofrequency energy eliminated AV nodal reentrant tachycardia in all patients. There were no significant differences in sinus cycle length (815 ± 159 msec vs 813 ± 162 msec;P = NS) and fast pathway conduction properties before and 1 week after ablation. Slow pathway conduction was completely eliminated in 10 (31%) (group I) of 32 patients after ablation. In the remaining 22 patients residual slow pathway conduction associated with one AV node echo was observed. In 15 patients (47%) (group II), the effective refractory period of the slow pathway showed a change of < 30 msec (265 ± 51 vs 266 ± 51 msec; P = NS), and in 7 patients (22%) (group III), a prolongation of more than 80 msec (247 ± 56 vs 340 ± 42 msec; P = 0.0001) before and 1 week after ablation. Minimal and maximal A2‐H2 interval over the slow pathway in group II was not significantly changed (Min A2‐H2:241 ± 37 vs 247 ± 40 msec; P = NS, Max A2‐H2: 346 ± 79 vs 350 ± 60 msec; P = NS), while a significant prolongation was measured in group III (Min A2‐H2: 261 ± 53 VS 373 ± 107 msec; P < 0.01. Max A2‐H2: 359 ± 41 vs 427 ± 63 msec; P < 0.05) before and after ablation. Conclusion: In group II patients there was no evidence shown of impairment of the slow pathway. This suggests that disruption of the link between fast and slow pathways may be responsible for the elimination of AV nodal reentrant tachycardia, besides the elimination or impairment of the slow pathway itself, in “slow pathway potential” guided catheter ablation, and that the slow pathway potential may not necessarily represent activation of the slow pathway itself or of its atrial connection.