Takuro Takagi

Polytetrafluoroethylene-covered stent and coronary artery aneurysms.

Angiographically detected coronary aneurysms (i.e., coronary segment greater then 1.5 times the normal artery) have an incidence of 0.3%–4.9% among patients undergoing coronary angiography and have been reported after an intervention procedure with a frequency of 2%–10%. The indication for treatment and the best modality still need to be defined. Some authors reported the successful treatment of coronary aneurysms with the polytetrafluoroethylene (PTFE)‐covered stent implantation, supporting the role of this strategy. In our institution, from September 1997 to December 1999 eight PTFE‐covered stents were implanted to treat seven coronary aneurysms in seven patients. All aneurysms were successfully treated by the PTFE‐covered stent. In one case, there was the necessity of an additional PTFE stent to cover the aneurysm completely. In no case did the loss of stent occur. No in‐hospital MACE occurred. At 35 ± 8 (21–44) months, six patients were symptom‐free. Angiographic follow‐up was performed in all patients at 10 ± 6 months. Restenosis occurred in one patient (14%) who had repeat percutaneous coronary interventions. This preliminary experience suggests that PTFE‐covered stent may be useful in the treatment of coronary artery aneurysms. Cathet Cardiovasc Intervent 2002;55:326–330.

Chronic stent recoil plays an important role in restenosis of the right coronary ostium.

ObjectiveThe efficacy of coronary stenting of aorto-ostial atherosclerotic lesions is still unclear. We investigated the frequency and mechanism of stent restenosis at this particular lesion. MethodsFifty-five consecutive patients with 64 native aorto-ostial lesions in the right coronary artery (RCA, n=38) and the left main trunk (LM, n=26) were treated by conventional stenting. Determinants of angiographic restenosis were established. The mechanism of stent restenosis was evaluated using post-stenting and follow-up intravascular ultrasound (IVUS) findings. ResultsRestenosis was more frequent in the RCA than in the LM (50% compared with 19%, P<0.03) and determinants included diabetes mellitus (63% compared with 21%, P<0.03), calcium deposition (58% compared with 5%, P<0.003), smaller stent cross-sectional area (SA) (as demonstrated by post-stenting IVUS studies, 8.1±1.4 mm2 compared with 10.2±2.2 mm2, P<0.01), larger plaque burden (64±6% compared with 57±8%, P<0.03) and less circular expansion at the aorto-coronary junction. Serial IVUS examination was performed in 11 patients with restenosis of the right coronary ostium. The mean reduction in the SA was 21% at the aorto-coronary junction (6.4±1.9 mm2, P<0.003), whereas the SA at the distal edge was unchanged. Thirty-three per cent of late luminal loss was due to chronic stent recoil. ConclusionThese findings suggest that stenosis of the right coronary ostium is a high-risk lesion for stent restenosis. In addition to excessive intimal growth, chronic stent recoil might be an important etiologic factor at this particular location.

A new dedicated stent and delivery system for the treatment of bifurcation lesions: Preliminary experience

We report the first clinical experience in eight patients with a new stent and delivery system specifically designed for the treatment of bifurcational lesions. The device (AST SLK‐View system) consists of a premounted stent and a delivery system. The stent has a side aperture, which orients toward the ostium of the side branch. The system allows deployment of the stent while the access to both main and side branches is maintained by two wires. We evaluated this system in nine bifurcations. The location of bifurcations was left descending artery/diagonal branch in four lesions, left circumflex/obtuse marginal branch in three lesions, and postero‐lateral branch/posterior descending artery in two lesions. Predilation was performed in six lesions of the main branches and in five lesions of the side branches. The stent was effectively delivered to all bifurcations except for one, in which the target lesion was located at a distal segment and the device could not be delivered. Following stent implantation in the main branch, two lesions at the side branches were treated by stent, while the other lesions were treated by balloon angioplasty without difficulty. Final kissing balloon was performed in four bifurcation lesions. No adverse event was observed during 1 month of clinical follow‐up. Treatment of bifurcation lesions with this new dedicated device appears to be feasible. This new device may introduce a new approach for the treatment of coronary bifurcation lesions. Cathet Cardiovasc Intervent 2003;58:34–42.

Sirolimus-eluting stents: a review of experimental and clinical findings

Sirolimus (Rapamycin) ist ein Makrolidantibiotikum mit zusätzlichen, sehr potenten immunsuppressiven Eigenschaften. Durch eine Hemmung der G1-Phase wird das Fortschreiten des Zellzyklus in die DNA-Synthesephase (S-Phase) unterbunden. Im Tierexperiment konnte gezeigt werden, dass Sirolimus nach Gefäßverletzung durch Ballondilatation zu einer effektiven Inhibition der Proliferation und Migration glatter Muskelzellen (SMC) führt. Aufgrund dieser ermutigenden Ergebnisse wurde die klinische Anwendung von Sirolimus freisetzenden Stents in einer Pilotstudie an 45 Patienten (FIM-Registratur) in Sao Paulo und Rotterdam initiiert. Desweiteren wurde eine randomisierte, placebokontrollierte, europaweite Multicenterstudie an 238 Patienten (RAVEL) durchgeführt. Beide zeigten, sowohl angiographisch als auch mittels intravaskulärem Ultraschall, eine nahezu vollständige Elimination der Neointimaformation bis zu einem Jahr nach der Indexprozedur. Diese Übersichtsarbeit beschreibt die experimentiellen und klinischen Ergebnisse von Studien mit Sirolimus freisetzenden Stents einschließlich unserer eigenen Erfahrungen von 26 Stents, die bei 17 Patienten implantiert worden waren. Nach elektiver Implantation an de-novo-Läsionen zeigten sich in den angiographischen und sonographischen Verlaufsuntersuchungen erstaunlich gut erhaltene Gefäßlumina. Neu entstandene Läsionen außerhalb der Zielläsion und späte Thrombosen wurden nach zweimonatiger Behandlung mit Acetylsalicylsäure und Ticlopidin oder Clopidogrel nicht beobachtet. Laufende Studien an größeren Patientenkollektiven werden zeigen, ob Sirolimus freisetzende Stents auch an Läsionen mit einem hohen Restenoserisiko (beispielsweise langstreckige Stenosen, Bifurkationsläsionen oder Instent-Rezidivstenosen) wirksam sind. Sirolimus (rapamycin), a macrolide antibiotic with known potent immunosuppressive properties, acts in the first phase (G1) of the cell cycle, blocking its further progression to the phase of DNA synthesis (S). In experimental models, rapamycin is effective in inhibiting smooth muscle cell proliferation and migration after vessel wall injury with balloon angioplasty. These results lead to the clinical application of sirolimus-eluting stents in 45 patients in Sao Paulo and Rotterdam (FIM Registry) and 238 patients in a randomized, European multicenter trial (RAVEL). These trials showed, by angiography and intravascular ultrasound, almost complete abolition of in-stent late hyperplasia up to one year after the procedure. In this review, we describe the experimental and clinical results of sirolimus-eluting stents including our experience of 26 stents implanted in 17 patients. In elective de novo lesions has shown remarkably clear lumens at follow-up angiography and intravascular ultrasound within the stented segments were observed with no lesion progression at the stent margins or thrombosis after a 2 month regimen of aspirin, and ticlopidine or clopidogrel. New large-scale ongoing clinical trials will investigate the efficacy of sirolimus-eluting stents in lesions that are traditionally associated with high restenosis rates after stent implantation, such as long lesions, bifurcations and in-stent restenosis.

Impact of Continuous Deterioration of Kidney Function 6 to 8 Months After Percutaneous Coronary Intervention for Acute Coronary Syndrome

Preprocedural chronic kidney disease and contrast-induced acute kidney injury are predictors of in-hospital death and long-term mortality. However, neither the time course of kidney function after percutaneous coronary intervention (PCI) nor the relation between the time course of kidney function and prognosis has been adequately studied. We studied 531 patients who underwent PCI for acute coronary syndrome. The continuous deterioration of kidney function (CDKF) was defined as a >25% increase in serum creatinine level or serum creatinine >0.5 mg/dl above baseline at 6 to 8 months after PCI. CDKF was observed in 87 patients (16.4%). Independent risk factors for CDKF were contrast-induced acute kidney injury, preprocedural hemoglobin level, and proteinuria. Patients with CDKF exhibited significant higher 5-year mortality rate than patients without CDKF (25% vs 9.4%, log-rank p = 0.0006). Independent risk factors for 5-year mortality were age >75 year, anemia, New York Heart Association class III or IV, low ejection fraction, and CDKF. CDKF is associated with an increased risk of all-cause mortality of 5 years in patients with acute coronary syndrome undergoing PCI.

Percutaneous bare Z-stent implantation as an alternative to surgery for acute aortic dissection with visceral ischemia

We describe a case of Stanford type B acute aortic dissection causing visceral ischemia. An aortogram showed an hourglass‐like narrowing of the true lumen at the diaphragm with a 60 mm Hg pressure gradient. Placement of a self‐expanding metallic Z‐stent under intravascular ultrasound guidance restored blood flow to the viscera. Cathet Cardiovasc Intervent 2003;58:95–100.

Aggressive statin therapy in multicenter and effectiveness for the reduction of intra-myocardial damage caused by non-ST elevation acute coronary syndrome: AMERICA study

Background: While preprocedural statin treatment for acute coronary syndrome (ACS) is widely regarded as beneficial, there has been no prospective randomized multicenter trial of patients with non-ST elevation ACS in the Japanese population to examine the efficacy of preprocedural aggressive statin use. The aim of this study was to confirm this effect by prospective randomized multicenter design. Methods: Fifty patients who presented with non-ST elevation ACS were enrolled, and randomly assigned to aggressive statin administration before percutaneous coronary intervention (PCI). Troponin-T (TnT), creatine phosphokinase (CK), CK-myocardial band (CK-MB), high-sense C-reactive protein (hs-CRP), and brain natriuretic peptide (BNP) were measured at baseline and/ or after procedure. Results: Three days after PCI, the statin group had significantly less CK elevation compared with the nonstatin group (84±17 IU/l versus 180±68 IU/l, respectively, p = 0.02). CK-MB elevation also tended to be lower in the statin group than in the nonstatin group (3.2±1.9 versus. 7.0±3.0, respectively, p = 0.07), as was BNP level (3.2±1.9 versus 7.0±3.0 pg/ml, respectively, p = 0.07). The change of serum LDL cholesterol was significantly correlated with CK (p = 0.01) and TnT (p = 0.02) at 1 day after PCI. Conclusions: Aggressive statin usage before PCI to Japanese patients with non-ST elevation ACS appears to reduce myocardial damage after procedure. The degree of serum lipid level reduction may reflect the vulnerability of atheromatous plaques that could cause cardiac damage after PCI.

Stent deformation: an experimental study of coronary ostial stenting☆

OBJECTIVES To investigate stent deformation by torsional stress after implantation at the ostium of a model coronary artery. BACKGROUND Little is known about coronary stent deformation, especially the association between stent design and deformation at the coronary ostium. Recent reports have suggested that mechanical factors are important for stent restenosis. METHODS A coronary ostium model was constructed and three different stents (Express(2), Cypher, and Tsunami, n=5 each) were implanted at the aorto-ostial junction. Differences of stent deformation were assessed after exposure to torsional stress. Intravascular ultrasound was used to measure the luminal area along each stent. Then the extent and pattern of plastic deformation were compared between the three stent types. RESULTS The Express(2) stents and Cypher stents both showed significant deformation (P<.0001 and P=.045, respectively) adjacent to the ostium, whereas only a minimal decrease of luminal area was observed with the Tsunami stent. In the central and distal parts of each stent, the decrease of luminal area was minimal and no differences were noted among the three types. Sudden fracture of a Cypher stent strut occurred during the experiment. CONCLUSION Differences of structural characteristics influence permanent plastic deformation at sites where continuous stress occurs, such as the coronary ostium. A more elastic design may show better resistance to such stress.

Contents of second peak in the circadian variation of acute myocardial infarction in the Japanese population

BACKGROUND Circadian variation has been accepted as a factor in acute myocardial infarction (AMI). An increased incidence of cardiac events in the morning has been reported for a long time. Recent reports have indicated that the onset of AMI shows two peaks, which occur in the morning and evening. It has also been demonstrated that circadian pattern of AMI may vary with sex and age. METHODS AND RESULTS We investigated 522 consecutive patients who underwent primary percutaneous coronary intervention (PCI) for ST segment elevation myocardial infarction (STEMI) between 2000 and 2010. The patients were classified into 3 age groups: younger (≤59 years old), intermediate (60-79 years old), and older (≥80 years old). Clinical data were investigated, including the age and sex, angiographic characteristics, and time of onset of STEMI. There were two peaks in the onset of STEMI throughout the day, which were at 7:00-10:00 and 19:00-21:00 h, among all patients (male and female). Stratified analysis showed that older females formed the main part of the second peak. CONCLUSIONS There were two peaks in the onset of STEMI in a Japanese population in Tokyo. The second peak was significantly dominated by the older female group. Age and gender influenced the second peak in the circadian variation of AMI in a Japanese population in Tokyo.

Bilateral spontaneous renal artery dissection

Spontaneous renal artery dissection is a rare condition that precedes renal infarction. We describe a 48-year-old, normotensive healthy woman presenting with left flank pain of sudden onset. Enhanced abdominal computed tomography demonstrated a dissecting intimal flap of the left renal artery complicating renal infarction. Doppler ultrasonography, selective angiography, and intravascular ultrasound revealed a dissecting intimal flap, with a large false lumen and narrow true lumen, of the renal artery bilaterally. Conservative management was undertaken with anticoagulant and analgesic therapy, and the patient was discharged after an uneventful clinical course.