Successful Management of a Resistant, Focal Calcified Lesion Following Direct Coronary Stenting With a Cutting Balloon

Direct stenting is a feasible and safe technique, which may reduce the procedure time, cost and radiation exposure as well as result with less vessel injury. However, it is not suitable for coronary lesions with excessive calcification, severe proximal tortuosity or in small caliber vessels. We describe a patient with a heavily calcified lesion that was not apparent by fluoroscopy, and in which the high-pressure inflation of the stent balloon failed to fully expand the stent, but cutting balloon inflations with incremental balloon sizes and high pressure achieved full expansion of the stent. Case Report. A 52-year-old man was hospitalized with unstable angina. Severe left ventricular dysfunction was noted with diffuse hypokinesia. Coronary angiography revealed a severe stenotic lesion in the mid-right coronary artery (RCA) and diffuse, irregular and moderate stenosis of its distal branches (Figure 1A). There were also severely narrow lesions in the mid-left anterior descending (LAD) and distal left circumflex (LCX) arteries. However, no apparent calcification was noted. The mid-RCA lesion was first selected for coronary angioplasty because it was a discrete and tight lesion. A NIR-SOX™ stent (Boston Scientific SCIMED, Maple Grove, Minnesota) was chosen for direct stenting because of its definite advantage in crossing tight stenotic segments. We used a 7 French Hockey Stick guiding catheter (Cordis, Miami, Florida) and the lesion was easily crossed with a 0.014-inch Choice floppy guidewire (Boston Scientific SCIMED). A 4.0 16 mm NIR-SOX stent was positioned at the lesion and inflated to 17 atm for 40 seconds. However, the stent was not completely expanded at the middle segment of the lesion and maintained an hourglass appearance (Figure 1B). A conventional and non-compliant angioplasty balloon (NC Viva, Boston Scientific SCIMED) with a 4.0 mm diameter that was inflated up to 20 atm for 60 seconds did not produce any significant improvement. Therefore, we decided to use a cutting balloon with incremental balloon sizes. Two inflations at 16 atm with a 3.0 mm diameter cutting balloon (IVT, Lotterkenny, Ireland) were performed and resulted in a slight improvement of stent expansion (Figure 1C). The balloon was replaced with a 3.75 mm diameter cutting balloon and inflated at 16 atm for 60 seconds, dilating the stent and leaving a 40% residual stenosis. Finally, 2 inflations with a 4.0 mm diameter cutting balloon at 16 atm of pressure dilated the stent, leaving a 20% residual stenosis. Additional inflations with a 4.5 mm diameter conventional and non-compliant angioplasty balloon (NC Viva, Boston Scientific SCIMED) up to 20 atm was necessary to obtain good angiographic results with a residual stenosis of 10% (Figure 1D). After the final balloon dilation, the IVUS revealed severe, focal circumferential calcification which appeared to be ruptured at the site of resistance (Figure 2A). At 6 months follow-up, angiography revealed good patency of a stent without restenosis (Figure 2B). Discussion. Direct stenting is successfully accomplished in a variety of clinical situations in selected coronary lesions and results in lower restenosis rates. Observational studies of direct stenting have demonstrated that this strategy is safe and feasible and has potential advantages including a shortened procedure time, decreased radiation exposure and a decreased contrast load.^1,2 The reduced ischemic times may lessen the subtle myocardial damage and the avoidance of balloon dilatation before stenting may reduce the extent of vessel injury and the subsequent restenotic response. However, it should be kept in mind that coronary arteries with visible calcifications and proximal tortuosity should be excluded from direct stenting. Calcific lesions carry the risk of inadequate stent expansion because of reduced vessel distensibility, and fibrocalcific plaques have been found to lower the degree of stent expansion.³ Therefore, the proper selection of lesions is of crucial importance for direct stenting. In our case, the calcification was not initially noted during the angiogram, but a severe, focal and circumferential calcification was revealed at the target lesion by post-procedural intravascular ultrasound (IVUS). Several new techniques, including rotational atherectomy and cutting balloon angioplasty (CBA), have been used for the treatment of calcified lesions. Rotational atherectomy is known to debulk calcified lesions effectively, resulting in increased compliance and a cylindrical geometry of the treated vessel. The advantage of the cutting balloon is its ability to reduce vessel stretch and vessel injury by scoring the vessel longitudinally rather than causing an uncontrolled disruption of the atheroscleotic plaque. Moreover, in management of in-stent restenosis (ISR), there appears to be a consistent advantage for CBA over PTCA in reducing restenosis and target vessel revascularization, owing to a greater acute gain in the lumen cross-sectional area.^4,5 Therefore, CBA may offer a relatively simple and effective option for ISR management. In our case, we selected CBA because it was easier to handle and more quickly accessible than the other techniques in our laboratory. A small diameter cutting balloon was chosen initially and then incrementally replaced by larger ones. Generally, low balloon inflation pressures (4–8 atm) are recommended for cutting balloons. However, we needed 20 atm of inflation pressures to achieve the full expansion of a stent. Our case showed that it is important to check for the presence of calcification at the lesion prior to performing direct stenting, and demonstrated the utility of incremental upsizing of the CBA when incomplete expansion of the stent occurs due to a circumferential, heavily and calcified lesion.

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