発症からの経過時間別にみた各心筋傷害マーカーの診断精度

発症早期の診断にはH-FABPが有用であるが特異度に限界があり、発症4時間以降は心筋トロポニンが感度・特異度ともに高く、診断に有用である。

胸痛の鑑別診断

胸痛を訴える疾患には、虚血性心疾患以外に心大血管系の疾患や消化器疾患、呼吸器疾患、さらに皮膚・骨格疾患が挙げられる。急性心筋梗塞のほかに緊急性を要する疾患には急性肺血栓塞栓、急性大動脈解離、急性心筋炎が挙げられる。

心電図でST上昇を認める疾患・病態

ST上昇を認める疾患には緊急治療を要するものから要しない疾患・病態まで含まれ、ほかの臨床所見と併せて総合的に診断することが大切である。

初期評価項目のチェックリスト

初期評価時のチェックすべき項目を表に示す。

背側部誘導（V7-9誘導）

V7-9誘導はV4誘導と同じ高さで、V7誘導は後腋下線との交点、V8誘導は左肩甲骨中線との交点、V9誘導は脊椎左縁との交点に付ける。
出典
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1: Importance of posterior chest leads in patients with suspected myocardial infarction, but nondiagnostic, routine 12-lead electrocardiogram.
著者: J B Agarwal, K Khaw, F Aurignac, A LoCurto
雑誌名: Am J Cardiol. 1999 Feb 1;83(3):323-6.
Abstract/Text: Criteria for reperfusion therapy in acute myocardial infarction require the presence of ST elevation in 2 contiguous leads. However, many patients with myocardial infarction do not show these changes on a routine 12-lead electrocardiogram and hence are denied reperfusion therapy. Posterior chest leads (V7 to V9) were recorded in 58 patients with clinically suspected myocardial infarction, but nondiagnostic routine electrocardiogram. ST elevation >0.1 mV or Q waves in > or =2 posterior chest leads were considered to be diagnostic of posterior myocardial infarction. Eighteen patients had these changes of posterior myocardial infarction. All 18 patients were confirmed to have myocardial infarction by creatine phosphokinase criteria or cardiac catheterization. Of the 17 patients who had cardiac catheterization, 16 had left circumflex as the culprit vessel. We conclude that posterior chest leads should be routinely recorded in patients with suspected myocardial infarction and nondiagnostic, routine electrocardiogram. This simple bedside technique may help proper treatment of some of these patients now classified as having unstable angina or non-Q-wave myocardial infarction.
Am J Cardiol. 1999 Feb 1;83(3):323-6.

虚血性心疾患がなく心筋トロポニンが上昇する病態

心筋トロポニンが上昇していても、冠動脈病変があるとは限らない。心筋トロポニンの上昇はあくまでも心筋傷害を反映するものであり、その原因までは特定できず、ほかの臨床所見と併せて総合的に診断することが大切である。
出典
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1: Universal definition of myocardial infarction.
Eur Heart J. 2007 Oct;28(20):2525-38. doi: 10.1093/eurheartj/ehm355.

診断時間帯別にみたトロポニンの高感度測定系と従来測定系の診断精度の比較

ROC曲線下面積で評価した急性心筋梗塞の診断精度は、高感度トロポニンが従来のトロポニンに比べ良好で、特に両者の差は超急性期ほど顕著である。
出典
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1: Early diagnosis of myocardial infarction with sensitive cardiac troponin assays.
著者: Tobias Reichlin, Willibald Hochholzer, Stefano Bassetti, Stephan Steuer, Claudia Stelzig, Sabine Hartwiger, Stefan Biedert, Nora Schaub, Christine Buerge, Mihael Potocki, Markus Noveanu, Tobias Breidthardt, Raphael Twerenbold, Katrin Winkler, Roland Bingisser, Christian Mueller
雑誌名: N Engl J Med. 2009 Aug 27;361(9):858-67. doi: 10.1056/NEJMoa0900428.
Abstract/Text: BACKGROUND: The rapid and reliable diagnosis of acute myocardial infarction is a major unmet clinical need.
METHODS: We conducted a multicenter study to examine the diagnostic accuracy of new, sensitive cardiac troponin assays performed on blood samples obtained in the emergency department from 718 consecutive patients who presented with symptoms suggestive of acute myocardial infarction. Cardiac troponin levels were determined in a blinded fashion with the use of four sensitive assays (Abbott-Architect Troponin I, Roche High-Sensitive Troponin T, Roche Troponin I, and Siemens Troponin I Ultra) and a standard assay (Roche Troponin T). The final diagnosis was adjudicated by two independent cardiologists.
RESULTS: Acute myocardial infarction was the adjudicated final diagnosis in 123 patients (17%). The diagnostic accuracy of measurements obtained at presentation, as quantified by the area under the receiver-operating-characteristic curve (AUC), was significantly higher with the four sensitive cardiac troponin assays than with the standard assay (AUC for Abbott-Architect Troponin I, 0.96; 95% confidence interval [CI], 0.94 to 0.98; for Roche High-Sensitive Troponin T, 0.96; 95% CI, 0.94 to 0.98; for Roche Troponin I, 0.95; 95% CI, 0.92 to 0.97; and for Siemens Troponin I Ultra, 0.96; 95% CI, 0.94 to 0.98; vs. AUC for the standard assay, 0.90; 95% CI, 0.86 to 0.94). Among patients who presented within 3 hours after the onset of chest pain, the AUCs were 0.93 (95% CI, 0.88 to 0.99), 0.92 (95% CI, 0.87 to 0.97), 0.92 (95% CI, 0.86 to 0.99), and 0.94 (95% CI, 0.90 to 0.98) for the sensitive assays, respectively, and 0.76 (95% CI, 0.64 to 0.88) for the standard assay. We did not assess the effect of the sensitive troponin assays on clinical management.
CONCLUSIONS: The diagnostic performance of sensitive cardiac troponin assays is excellent, and these assays can substantially improve the early diagnosis of acute myocardial infarction, particularly in patients with a recent onset of chest pain. (ClinicalTrials.gov number, NCT00470587.)

2009 Massachusetts Medical Society
N Engl J Med. 2009 Aug 27;361(9):858-67. doi: 10.1056/NEJMoa0900428.

ST上昇型急性心筋梗塞の診断アルゴリズム