Key result
Intracoronary nitroglycerin abruptly resolves severe coronary vasospasm mimicking acute occlusion via the clasp-knife sign.
Why the study?
Coronary vasospasm can mimic acute coronary occlusion and STEMI, potentially leading to unnecessary interventions if not recognized.
Case Report (n=1)
Intracoronary administration of nitrates prior to mechanical intervention in cases of apparent coronary occlusion can reveal functional vasospasm characterized by a dynamic 'clasp-knife sign', thus preventing unnecessary stenting.
BACKGROUND: Coronary vasospasm may mimic acute coronary occlusion and ST-segment elevation myocardial infarction, potentially leading to unnecessary interventions if not recognized. CASE SUMMARY: A 32-year-old woman with no prior medical history presented with acute chest pain and inferior ST-segment elevation. Emergency coronary angiography demonstrated apparent complete occlusion of the proximal right coronary artery with absent distal flow. Before any mechanical intervention, intracoronary nitroglycerin was administered, resulting in abrupt restoration of vessel patency with normalization of luminal caliber and TIMI flow grade 3. This dynamic change created a characteristic appearance resembling the sudden opening of a clasp knife. The patient was managed conservatively with vasodilator therapy and remained clinically stable. DISCUSSION: This case highlights a distinctive angiographic manifestation of coronary vasospasm. Recognition of this phenomenon, termed the clasp-knife sign, may help differentiate vasospastic occlusion from thrombotic coronary obstruction and prevent unnecessary coronary intervention.
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Sezgin et al. (2026) conducted a case report in Coronary vasospasm (n=1). Intracoronary nitroglycerin was evaluated on Resolution of coronary occlusion and restoration of normal luminal caliber. Intracoronary nitroglycerin administration abruptly resolved severe coronary vasospasm that mimicked an acute thrombotic occlusion, producing a characteristic rapid angiographic reopening termed the clasp-knife sign.
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