during percutaneuos coronary intervention ( pci ) procedures , several complications can occur , such as dissections , thrombi , ulcers or plaque , may appear as angiographic hazy or uncertain images .
a proper diagnosis is important to guide the correct management in the catheterization laboratory and to improve patient outcomes .
angiography has important limitations to characterize those entities that , with contrast , can be diagnosed accurately thanks to intravascular imaging.1 ) among the intracoronary imaging techniques available , intravascular ultrasound ( ivus ) and optical coherence tomography ( oct ) are the most commonly used for research .
both techniques provide great value for characterization of coronary lesions and for guidance of pci .
ivus is very useful to measure the vessel wall and to evaluate plaque burden , whereas the oct ( with almost microscopic resolution ) is an excellent method for characterizing luminal and intimal lesions.2 - 4 ) herein , we present a case that illustrates the ability of oct for accurate diagnosis of an intracoronary post - angioplasty that had an uncertain hazy image , and its usefulness as a guide for therapeutic strategy .
a 73-year - old female patient underwent coronary angiography after being admitted with a non - st elevation myocardial infarction .
we determined that the patient had 2 diseased coronary vessels , with the culprit lesion in the right coronary artery ( rca ) and a severe lesion in the left anterior descending artery ( lad ) ( fig .
1 ) . we treated the rca lesion with implantation with a bare metal stent ( bms ) .
ten hours before the second procedure , the patient was given a sub - cutaneous dose of 1 mg / kg enoxaparin .
following the current recommendation guidelines,5 ) we gave the patient a 0.3 mg / kg enoxaparine dose by intravenous administration immediately before the angioplasty procedure ; we decided against giving the patient unfractionated heparin .
we performed a predilatation procedure using a compliant balloon angioplasty in the lad without angiographic complications , and after that we implanted a bms of 2.523 mm . in the control post - pci angiography
because of the uncertain interpretation by angiography , we decided to perform oct in order to ascertain the mechanism of the angiographic hazy image ( dissection , thrombus , plaque prolapse ) .
we used a c7-xr , saint jude oct frequency domain system with a dragon fly catheter ( st .
the oct study showed an intra - stent protruding signal rich mass with irregular borders and low - backscattering , a finding compatible with a white thrombus .
the stent was fully expanded but showed some strut malapposition at the proximal border ( fig .
the final result was significant reduction of the thrombus and correction of the stent malapposition ( fig .
the patient was discharged 3 days after the procedure and did not experience any additional clinical events . at 4 months
acute stent thrombosis may occur in patients , with or without acute coronary syndrome.4)6 - 12 ) rinaldi et al.6 ) identified 4 independent predictors of stent thrombosis during pci : higher baseline platelet count , acute myocardial infarction indication , use of a coil or self - expanding stent , and preprocedural thrombus . in this particular case ,
a great thrombus burden was found during the first acute pci performed in the rca , but no angiographic thrombotic images that were found suggested lad thrombosis prior to pci .
we had not performed an initial oct , so a possible previous thrombus could be present , but had remained undetected by angiography . however , we consider that a high - risk patient , the stent malapposition and possibly an inadequate anticoagulation could explain the acute stent thrombosis . an alternate explanation , such as prolapsed thrombus , could not be dismissed without a previous oct .
an incorrect diagnostic leads to an incorrect choice in therapeutics and potential damage to the patient .
the choice of ivus or oct in order to obtain a specific diagnosis of an intravascular lesion depends in most of the cases on the availability and or experience in the laboratory .
the oct has a spatial resolution of about 10 - 15 m with a penetration depth of 2 to 3 mm .
the frequency - domain oct modality , allows for high - resolution imaging , with pullbacks of 50 mm in less than 3 seconds , with minimum use of contrast and without coronary occlusion requirement.2)3 ) oct allows the characterization of histologic composition of the lesion and a precise identification of the luminal border , with high sensitivity to detect tiny dissections , plaque prolapse or intraluminal thrombus ( even to distinguish white and red thrombus).2 - 4)7 - 12 ) in contrast , ivus has a spatial resolution much lower , around 130 m , and does not allow the accurate characterization of some intravascular images.4)8)9 ) comparing both intravascular image techniques and after performing pci in their study , kawamori et al.8 ) could identify thrombus in 15% with oct , and 5% with ivus . in the setting of pci for acute coronary syndrome kubo et al.9 ) could detect thrombus in all patients with oct , but only in 33% of patients with ivus . in this case ,
discrimination between dissections , plaque prolapsed , or thrombus was crucial to the choice of treatment . a dissection would have required a new stent implantation , and it would certainly have contraindicated thrombus aspiration .
optical coherence tomography is a straightforward and useful method to assess misleading angiographic lesions , probably with higher accuracy than ivus when scanning intravascular or intra - stent images , and may be useful during pci procedures when angiography is uncertain .
 although its use in daily practice is not common , optical coherence tomography ( oct ) is a powerful research tool in invasive cardiology . 
 this report describes a hazy angiography image after percutaneous coronary intervention that has been assessed using oct . 
 based on the results of the oct , the patient underwent an elective coronary angioplasty with standard anticoagulation . 
 after implantation of the stent , an intracoronary hazy image was seen on angiography . 
 the use of oct permitted a correct diagnosis and a successful treatment . 
 this paper provides a discussion of the advantages and disadvantages of oct , and a comparison with intravascular ultrasound . 
Introduction
Case
Discussion