This is a 69-year-old gentleman, he has known history of hypertension, hyperlipidaemia and impaired fasting glucose, currently on amlopidine and atorvastatin. He complained of recurrent exertional angina for few months. He did not have any shortness of breath or heart failure symptoms. His family history was unremarkable. On physical examination, his JVP was normal, dual heart sound with no added murmur, his chest was clear on auscultation. 

ECG showed non-specific T inversions over V2-3 and inferior leads and his serial hsTnT were negative.

Coronary angiogram showed normal LMS and RCA, there was mild haziness at proximal LAD artery and an intermediate lesion at mid segment of LCx artery.
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Functional resting full-cycle ratio (RFR) was positive (0.82) for pLAD lesion and was negative (0.96) for mLCx lesion. To investigate the coronary haziness, optical coherent tomography (OCT) was performed to delineate the underlying cause of coronary ischemia. OCT imaging of pLAD demonstrated recanalization of an organized thrombus, thus it was suggestive of recent coronary thrombosis which was partially resolved. This was labelled as “Swiss Cheese” appearance with multiple small channels divided by thin septa surrounded by a larger central lumen. A drug-eluting stent (DES) 3.0x26mm was placed at pLAD to restore normal coronary flow and prevent future risk of thrombotic occlusion. 
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This case illustrated the beauty of OCT in sorting out the cause of coronary haziness. Recanalization of an organized thrombus is one of the important differential diagnoses that has to be considered, most of these lesions are functionally significant and require revascularization by stenting.