Severely calcified lipidic atheroma on intravascular ultrasound and near-infrared spectroscopy imaging: its association with slow-flow phenomenon during percutaneous coronary intervention

Macroscopic calcified lesion has been generally considered to be stable atheroma. In our case with coronary artery disease and a prior myocardial infarction, intravascular ultrasound (IVUS) and near-infrared spectroscopy (NIRS) imaging before percutaneous coronary intervention (PCI) visualized a severely calcified atheroma containing lipidic materials. Following lesion dilatation with a scoring balloon, the slow-flow phenomenon with ST-segment elevation and chest pain occurred. This case suggests that calcified plaque is not necessarily stable lesion but infrequently high-risk one which requires adjunctive management to prevent the slow-flow phenomenon during the procedure.

A 78-year-old asymptomatic gentleman with a prior inferior myocardial infarction (LVEF = 39%) was hospitalized to evaluate coronary stenosis on computed tomography. Coronary angiography identified an intermediate stenosis with severe calcification in the proximal left anterior descending artery (Figure 1 and Supplementary material online, Movie SI). Since the fractional flow reserve was 0.75 despite optimal medical therapy (aspirin 100 mg, rosuvastatin 5 mg, olmesartan 20 mg, and isosorbide dinitrate 40 mg), PCI was conducted after the commencement of clopidogrel 75 mg for 2 weeks. IVUS imaging demonstrated the presence of circumferential severe calcification (proximal and distal reference diameter were 4.0 and 3.7 mm, respectively) (Figure 1 and Supplementary material online, Movie SII). However, its maximum lipid core burden index in 4 mm (MaxLCBI_4 mm) on NIRS imaging was 959, indicating extensive lipidic materials behind calcification (Figure 1 and Supplementary material online, Movie SIII). Since rotablator use may cause no-reflow phenomenon_, we performed dilatation using a 3.5 × 15 mm scoring balloon (Scoreflex NC, OrbusNeich, Hong Kong) with high-pressure inflation (18 atm) under filter-wire use (Parachute™, GoodCare, Nagoya, Japan) (Figure 2). Following this procedure, no-reflow phenomenon occurred with chest pain and ST-segment elevation (troponin T level = 0.103 ng/ml) (Figure 2 and Supplementary material online, Movie SIV). A final TIMI III flow with optimal dilatation of the culprit lesion was achieved by retrieving the filter wire with intracoronary administration of 2 mg nicorandil and stent implantation (3.5 × 20 mm biodegradable polymer-coated everolimus-eluting stent: SYNERGY, Boston Scientific, Natick, MA, USA). He is uneventful for 18 months after PCI.

Figure 1.

Imaging of culprit lesion. Coronary angiography identified significant stenosis in the proximal of left anterior descending artery. Combined near-infrared spectroscopy/intravascular ultrasound imaging visualized the presence of lipidic component behind severe circumferential calcification (A–C). A near-infrared spectroscopy-derived chemogram illustrated that MaxLCBI_4 mm at the culprit lesion was 959. MaxLCBI_4 mm = maximum lipid core burden index in 4mm.

Figure 2.

Percutaneous coronary intervention procedure. Pre-dilatation was performed using a 3.5 × 15 mm scoring balloon (Scoreflex NC, OrbusNeich, Hong Kong) under filter-wire protection use (Parachute™, GoodCare, Nagoya, Japan) (left panel). Following balloon angioplasty, filter no-reflow occurred after pre-dilatation (right panel).

Given that calcified plaque is pathophysiologically formulated through deposition of lipidic material within vessel wall, calcified lesions can contain some amount of lipidic materials, which may affect PCI-related complications.¹ These observations indicate that calcified plaque is not necessarily stable lesion but infrequently high-risk one requiring preventive management for deterioration of coronary flow. Since IVUS is not capable to visualize plaque composition behind calcification,² this case suggests the clinical applicability of NIRS/IVUS imaging catheter to evaluate procedural risk at calcified lesions.

Supplementary material

Supplementary material is available at European Heart Journal - Case Reports online.

Consent: The author/s confirm that written consent for submission and publication of this case report including image(s) and associated text has been obtained from the patient in line with COPE guidance.

Conflict of interest: none declared.