Naoya Hamasaki

Bio: Naoya Hamasaki is an academic researcher from Memorial Hospital of South Bend. The author has contributed to research in topics: Restenosis & Stent. The author has an hindex of 16, co-authored 34 publications receiving 3309 citations. Previous affiliations of Naoya Hamasaki include MedStar Washington Hospital Center & Erasmus University Rotterdam.

Three-Year Follow-up after Implantation of Metallic Coronary-Artery Stents

Abstract: Background Coronary-artery stents are known to reduce rates of restenosis after coronary angioplasty, but it is uncertain how long this benefit is maintained. Methods We evaluated clinical and angiographic follow-up information for up to three years after the implantation of Palmaz–Schatz metallic coronary-artery stents in 143 patients with 147 lesions of native coronary arteries. Results The rate of survival free of myocardial infarction, bypass surgery, and repeated coronary angioplasty for stented lesions was 74.6 percent at three years. After 14 months, revascularization of the stented lesion was necessary in only three patients (2.1 percent). In contrast, coronary angioplasty for a new lesion was required in 11 patients (7.7 percent). Follow-up coronary angiography of 137 lesions at six months, 114 lesions at one year, and 72 lesions at three years revealed a decrease in minimal luminal diameter from 2.54±0.44 mm immediately after stent implantation to 1.87±0.56 mm at six months, but no further decre...

Remodeling of Human Coronary Arteries Undergoing Coronary Angioplasty or Atherectomy

Abstract: Background Recently, long-term constriction of the vessel has been suggested as an alternative mechanism of restenosis after coronary angioplasty. Methods and Results To understand remodeling of human coronary arteries undergoing coronary angioplasty or atherectomy, serial intravascular ultrasonographic examinations were performed at preintervention and postintervention examinations and at 24 hours, 1 month, and 6 months. Complete serial data were obtained in 61 lesions (balloon angioplasty, 35 lesions; directional atherectomy, 26 lesions). Lumen area improved from 6.81±2.24 mm2 after intervention to 8.22±2.79 mm2 at 1 month (P=.0001) and decreased to 4.88±2.86 mm2 at 6 months (P=.0001). Vessel area enlarged from 17.32±5.35 mm2 after intervention to 19.39±5.33 mm2 at 1 month (P=.0001) and decreased to 16.33±5.54 mm2 at 6 months (P=.0001). Plaque+media area increased significantly from postintervention examination to 24 hours (10.51±4.38 versus 10.96±4.49 mm2, P=.0008) and from 24 hours to 6 months (10.96±...

ACC/AHA guidelines for the management of patients with unstable angina and non-ST-segment elevation myocardial infarction: Executive summary and recommendations: A report of the American College of Cardiology/American Heart Association task force on practice guidelines (committee on the management of patients with unstable angina)

Abstract: The American College of Cardiology (ACC)/American Heart Association (AHA) Task Force on Practice Guidelines was formed to make recommendations regarding the diagnosis and treatment of patients with known or suspected cardiovascular disease. Coronary artery disease (CAD) is the leading cause of death in the United States. Unstable angina (UA) and the closely related condition non–ST-segment elevation myocardial infarction (NSTEMI) are very common manifestations of this disease. These life-threatening disorders are a major cause of emergency medical care and hospitalizations in the United States. In 1996, the National Center for Health Statistics reported 1 433 000 hospitalizations for UA or NSTEMI. In recognition of the importance of the management of this common entity and of the rapid advances in the management of this condition, the need to revise guidelines published by the Agency for Health Care Policy and Research (AHCPR) and the National Heart, Lung and Blood Institute in 1994 was evident. This Task Force therefore formed the current committee to develop guidelines for the management of UA and NSTEMI. The present guidelines supersede the 1994 guidelines. The customary ACC/AHA classifications I, II, and III summarize both the evidence and expert opinion and provide final recommendations for both patient evaluation and therapy: Class I: Conditions for which there is evidence and/or general agreement that a given procedure or treatment is useful and effective . Class II: Conditions for which there is conflicting evidence and/or a divergence of opinion about the usefulness/efficacy of a procedure or treatment. Class IIa: Weight of evidence/opinion is in favor of usefulness/efficacy. Class IIb: Usefulness/efficacy is less well established by evidence/opinion. Class III: Conditions for which there is evidence and/or general agreement that the procedure/treatment is not useful/effective and in some cases may be harmful. The weight of the evidence was ranked highest (A) if the data …

A Randomized Comparison of Coronary-Stent Placement and Balloon Angioplasty in the Treatment of Coronary Artery Disease

Abstract: Background Coronary-stent placement is a new technique in which a balloon-expandable, stainless-steel, slotted tube is implanted at the site of a coronary stenosis. The purpose of this study was to compare the effects of stent placement and standard balloon angioplasty on angiographically detected restenosis and clinical outcomes. Methods We randomly assigned 410 patients with symptomatic coronary disease to elective placement of a Palmaz-Schatz stent or to standard balloon angioplasty. Coronary angiography was performed at base line, immediately after the procedure, and six months later. Results The patients who underwent stenting had a higher rate of procedural success than those who underwent standard balloon angioplasty (96.1 percent vs. 89.6 percent, P = 0.011), a larger immediate increase in the diameter of the lumen (1.72 ±0.46 vs. 1.23 ±0.48 mm, P<0.001), and a larger luminal diameter immediately after the procedure (2.49 ±0.43 vs. 1.99 ±0.47 mm, P<0.001). At six months, the patients with stented ...

Sirolimus-eluting stents versus standard stents in patients with stenosis in a native coronary artery.

Abstract: Background Preliminary reports of studies involving simple coronary lesions indicate that a sirolimus-eluting stent significantly reduces the risk of restenosis after percutaneous coronary revascularization. Methods We conducted a randomized, double-blind trial comparing a sirolimus-eluting stent with a standard stent in 1058 patients at 53 centers in the United States who had a newly diagnosed lesion in a native coronary artery. The coronary disease in these patients was complex because of the frequent presence of diabetes (in 26 percent of patients), the high percentage of patients with longer lesions (mean, 14.4 mm), and small vessels (mean, 2.80 mm). The primary end point was failure of the target vessel (a composite of death from cardiac causes, myocardial infarction, and repeated percutaneous or surgical revascularization of the target vessel) within 270 days. Results The rate of failure of the target vessel was reduced from 21.0 percent with a standard stent to 8.6 percent with a sirolimus-eluting ...

Lessons From Sudden Coronary Death A Comprehensive Morphological Classification Scheme for Atherosclerotic Lesions

Abstract: This review will reconsider the current paradigm for understanding the critical, final steps in the progression of atherosclerotic lesions. That scheme, largely an outgrowth of observations of autopsy tissues by Davies and colleagues,1 2 asserts that the cause of death in atherosclerotic coronary artery disease is rupture of an advanced atherosclerotic lesion. Although this assumption may be partially true, recent autopsy studies suggest that it is incomplete. To reconsider this paradigm, we reexamined the morphological classification scheme for lesions proposed by the American Heart Association (AHA).3 4 This scheme is difficult to use for 2 reasons. First, it uses a very long list of roman numerals modified by letter codes that are difficult to remember. Second, it implies an orderly, linear pattern of lesion progression. This tends to be ambiguous, because it is not clear whether there is a single sequence of events during the progression of all lesions. We have therefore tried to devise a simpler classification scheme that is consistent with the AHA categories but is easier to use, able to deal with a wide array of morphological variations, and not overly burdened by mechanistic implications. The current paradigm is based on the belief that type IV lesions, or “atheromas,” described by the AHA are stable because the fatty, necrotic core is contained by a smooth muscle cell–rich fibrous cap. Virchow’s analysis5 in 1858 pointed out that historically, the term “atheroma” refers to a dermal cyst (“Grutzbalg”), a fatty …

The pathogenesis of coronary artery disease and the acute coronary syndromes (1).

Abstract: IN the 19th century there were two major hypotheses to explain the pathogenesis of atherosclerosis: the "incrustation" hypothesis and the "lipid" hypothesis. The incrustation hypothesis of von Rokitansky,1 proposed in 1852 and modified by Duguid,2 suggested that intimal thickening resulted from fibrin deposition, with subsequent organization by fibroblasts and secondary lipid accumulation. The lipid hypothesis, proposed by Virchow3 in 1856, suggested that lipid in the arterial wall represented a transduction of blood lipid, which subsequently formed complexes with acid mucopolysaccharides; lipid accumulated in arterial walls because mechanisms of lipid deposition predominated over those of removal. The two hypotheses are now . . .