坂倉 建一

AIMS: Restenosis in drug-eluting stents (DESs) occurs infrequently, however, it remains a pervasive clinical problem. We interrogated our autopsy registry to determine the underlying mechanisms of DES restenosis, and further we investigated the neointimal characteristics of DESs and compared with bare metal stents (BMSs). METHODS AND RESULTS: Coronary lesions from patients with DES implants (n = 82) were categorized into four groups based on cross-sectional area narrowing: patent (<50%), intermediate (50-74%), restenotic (≥ 75% with residual lumen), and total occlusion (organized thrombus within the stent). Restenosis and occlusion were significantly dependent on the total stented length: restenosis (26.7 mm) and occlusion (25.7 mm) compared with patent DESs (17.3 mm). Further, restenotic and occluded lesions were located more distally in the coronary arteries and had greater vessel injury and uneven strut distribution suggesting local drug gradient. Multivariate analysis revealed that normalized maximum inter-strut distance was associated with DES restenosis (OR: 17.4, P = 0.04) while medial tear length was a predictor of DES occlusion (OR: 5.1, P = 0.03). No differences were observed between different DESs (sirolimus-, paclitaxel-, and everolimus-eluting stents) for restenosis and occlusion. Further, neointimal compositions of restenotic DESs demonstrated greater proteoglycan deposition and less smooth muscle cellularity over time, when compared with BMS with greater cell density and collagen deposition. CONCLUSIONS: Our study indicates the impacts of inadequate drug concentration due to wider inter-strut distance and vessel injury as primary mechanisms of DES restenosis and occlusion, respectively. Moreover, the differences in neointimal compositions between DESs and BMSs might serve as a potential target for the suppression of late neointima growth via inhibition of proteoglycans in DESs.

The internal mammary artery (IMA) grafts have been associated with long-term patency and improved survival as compared to saphenous vein grafts (SVGs). Early failure of IMA is attributed to poor surgical technique and less with thrombosis. Similarly, bypass surgery especially with the use of IMA has also been shown to be superior at 1-year as well as over five years compared to percutaneous procedures, including the use of drug-eluting stents for the treatment of coronary artery disease. The superiority of IMAs over SVGs can be attributed to its striking resistance to the development of atherosclerosis. Structurally its endothelial layer shows fewer fenestrations, lower intercellular junction permeability, greater anti-thrombotic molecules such as heparin sulfate and tissue plasminogen activator, and higher endothelial nitric oxide production, which are some of the unique ways that make the IMA impervious to the transfer of lipoproteins, which are responsible for the development of atherosclerosis. A better comprehension of the molecular resistance to the generation of adhesion molecules that are involved in the transfer of inflammatory cells into the arterial wall that also induce smooth muscle cell proliferation is needed. This basic understanding is crucial to championing the use of IMA as the first line of defense for the treatment of coronary artery disease.

We report a rare case of fulminant myocarditis that was considered to have smoldered for a few months before it finally exteriorized. An 80-year-old man had had two episodes of mild congestive heart failure with preserved ejection function (HFPEF) within 3 months before he was finally admitted for the treatment of rapidly progressive heart failure. Cardiac function deteriorated remarkably on the final admission. Extracorporeal cardiopulmonary support was used because of pump failure and conduction disability, however, the patient died on the 16th day. Endomyocardial biopsy revealed numerous inflammatory infiltrates in myocardium compatible with fulminant myocarditis. However, advanced fibrosis and increased number of B lymphocytes and plasma cells found in the present case were not typical for fulminant myocarditis. Considering several distinctive findings in clinical and laboratory findings together, two preceding HFPEF episodes were highly likely to be associated with myocarditis.

たこつぼ心筋症(transient left ventricular apical ballooning, takotsubo cardiomyopathy; TTC) では診断時, 冠動脈の有意狭窄を除外基準とすることが多い. しかしながら, 高齢者に多い病気であり, 最近, 冠動脈に有意狭窄のあるたこつぼ心筋症の存在もいわれるようになってきた. 症例は83歳, 女性. 普段から行っているわけではない, 緊張を伴った神社参拝, 豆まきという行事直後の食事, 飲酒をした際に著明な冷汗と意識が遠のく感覚を自覚したため, 救急要請となり当センターに救急搬送された. 急性冠症候群(acute coronary syndrome; ACS)が疑われ, 緊急心臓カテーテル施行. 左冠動脈前下行枝(left anterior descending artery; LAD)#7に90％狭窄を認めたため, 緊急経皮的冠動脈形成術(percutaneous coronary intervention; PCI)を行った. 直後の左室造影(left ventriculography; LVG)では, LADの支配領域に合致しない左心室基部の過収縮と心尖部の無収縮を認め, 高度冠動脈狭窄を合併したTTCと診断された. TTCとLAD病変の関与したACSは最も重要な鑑別点である. ACSとして判断されていた症例の中にも実際には詳細に検討すると, たこつぼ心筋症が潜んでいる可能性があることを示唆している. また, 診断方法の感度を考慮すると, 疾患概念による形体描写に基づかない命名の必要性が指摘されている. 病態解明の進歩が, 今後一層期待される.