In addition to calcification, thrombus, and CTOs, other complex lesion types include:
- •
Spontaneous coronary artery dissection (SCAD) (PCI Manual Online case 72 ),
- •
Stent failure (in-stent restenosis and stent thrombosis),
CTO Manual Online cases: 19 , 52 , 54 , 58 , 72 , 84 , 91 , 101 ; PCI Manual Online cases: 63 , 89 , 94
- •
Small and large vessels, and
- •
Long lesions.
22.1
Spontaneous coronary artery dissection
SCAD is defined as an epicardial coronary artery dissection that is not associated with atherosclerosis or trauma and is not iatrogenic . The predominant mechanism of myocardial injury occurring as a result of SCAD is coronary artery obstruction caused by formation of an intramural hematoma (IMH) or intimal disruption rather than atherosclerotic plaque rupture or intraluminal thrombus .
22.1.1
Planning
SCAD should be suspected in young women, especially in the peripartum setting ( Fig. 22.1 ) .
22.1.2
Monitoring
Given high risk of complications and hemodynamic deterioration, careful monitoring is needed throughout the procedure.
22.1.3
Medications
Anticoagulation and oral antiplatelet therapy is administered as in non-SCAD cases. Glycoprotein IIb/IIIa inhibitors and cangrelor should generally be avoided given risk of extending an IMH.
22.1.4
Access
Femoral access is preferred for coronary angiography of patients with suspected SCAD, given a threefold higher risk for catheter-induced iatrogenic dissection with radial access observed in one series .
22.1.5
Engagement
Coronary engagement should be performed with extreme care aiming for coaxial positioning, and avoiding deep coronary artery intubation .
22.1.6
Angiography
Strong contrast injections should be avoided to reduce the risk of iatrogenic dissection .
Identification of SCAD can be challenging and requires awareness and careful angiographic interpretation. There are three angiographic types of SCAD ( Fig. 22.2 ) :
Type 1 : Classic appearance of multiple radiolucent lumens or arterial wall contrast staining.
Type 2 : Diffuse stenosis that can be of varying severity and length (usually >20 mm). Variant 2A is diffuse arterial narrowing bordered by normal segments proximal and distal to the IMH, and variant 2B is diffuse narrowing that extends to the distal tip of the artery.
Type 3 : Focal or tubular stenosis, usually <20 mm in length. Type 3 mimics atherosclerosis and requires intracoronary imaging (if safe) to diagnose SCAD.
22.1.7
Selecting target lesion(s)
PCI of SCAD lesions carries high risk of complications and is often quoted as “a temptation to be avoided.” Conservative management is preferred (if feasible), however in patients with active ischemia or hemodynamic instability coronary revascularization may be required, as follows :
- •
Stable patients without left main or proximal two-vessel coronary dissection: in-hospital observation for 3–5 days without revascularization.
- •
Stable patients with left main or proximal two-vessel coronary dissection: CABG versus continued in-hospital observation.
- •
Unstable patients or active ischemia: PCI or CABG depending on anatomy.
22.1.8
Wiring
Given the risk of subintimal guidewire entry, polymer-jacketed guidewires should be avoided in patients with suspected SCAD.
22.1.9
Lesion preparation
Direct stenting has been proposed for SCAD lesions to minimize the risk of IMH expansion. A cutting balloon can sometimes be used to decompress the hematoma, but it carries a risk of perforation.
The cutting balloon has been used for fenestration of an IMH with luminal compression at multiple sites prior to stenting .
22.1.10
Stenting
Implanting long stents that extend 5–10 mm on both sides of the IMH has been proposed in SCAD patients to minimize the risk of subintimal hematoma expansion . The stent diameter should generally be smaller than the size used in similar atherosclerotic lesions to avoid hematoma expansion.
22.1.11
Closure
Access closure is performed as described in Chapter 11: Access Closure .
22.1.12
Coronary physiology
Coronary physiology has limited role in SCAD cases.
22.1.13
Intravascular imaging
Intravascular imaging, especially OCT, can confirm the diagnosis of SCAD, but may also cause extension of the dissection and should, therefore, be used cautiously.
22.1.14
Hemodynamic support
Because of high risk of acute vessel closure during PCI of SCAD lesions, access to hemodynamic support devices, such as VA-ECMO is recommended (PCI Manual Online case 72 ).
22.2
Stent failure
Stent failure can manifest as stent thrombosis or in-stent restenosis . Stent thrombosis is a life-threatening complication and usually presents as ST-segment elevation acute myocardial infarction. In-stent restenosis usually presents with stable angina but can sometimes present as an acute coronary syndrome.
Stent thrombosis is often caused by stent underexpansion or insufficient antithrombotic therapy. Stent thrombosis is rarely caused by stent fracture.
22.2.1
Planning
Special emphasis should be given to a detailed history of prior percutaneous coronary interventions, including stent types, stent sizes, prior stent failure (stent thrombosis or in-stent restenosis), and prior brachytherapy [that requires lifelong dual antiplatelet therapy due to continued risk of very late (>1 year) stent thrombosis].
Moreover, it is important to know the current antiplatelet therapy and compliance with the therapy, any recent antiplatelet therapy discontinuation and any recent noncardiac surgery.
22.2.2
Monitoring
Given high risk of complications and hemodynamic deterioration of stent thrombosis patients, careful monitoring is needed throughout the procedure.
22.2.3
Medications
Lifelong dual antiplatelet therapy is recommended after development of stent thrombosis unless the patient is at high risk of bleeding.
Cilostazol may decrease the risk of in-stent restenosis, but is contraindicated in patients with heart failure.
22.2.4
Access
Radial or femoral access can be used. Radial access is generally preferred in stent thrombosis patients presenting with a STEMI.
22.2.5
Engagement
Performed as described in Chapter 5: Coronary and Graft Engagement .
22.2.6
Angiography
Performed as described in Chapter 6: Coronary Angiography .
Using X-ray image enhancing technologies, such as the StentBoost (Philips) or CLEARstent (Siemens) (by placing a balloon within the occluded stent) can help identify stent fracture or stent gap.
22.2.7
Selecting target lesion(s)
Stent thrombosis requires immediate PCI, as is standard for STEMI patients.
The type of revascularization of in-stent restenotic lesions depends on the type of restenosis, prior restenotic events, overall coronary anatomy and feasibility of coronary bypass graft surgery.
22.2.8
Wiring
Stent thrombosis: wiring can be challenging due to thrombus and is performed as described in Chapter 8: Wiring and Chapter 20: Acute Coronary Syndromes—Thrombus , Section 20.9 . Use of polymer-jacketed guidewires can facilitate crossing.
A unique potential challenge with wiring through prior stents (whether in the setting of stent thrombosis or in-stent restenosis) is guidewire passage under the struts of the previously implanted stent(s) (CTO PCI Manual case 143 ). This can manifest as difficulty advancing equipment and can often be prevented by advancing a knuckled guidewire through the prior stent.
Sometimes stent failure is due to stent fracture, which can be very challenging to wire through.
22.2.9
Lesion preparation
Meticulous lesion preparation (guided by intravascular imaging as described in Section 22.2.13 ) is critical prior to additional stent implantation. Stent underexpansion can lead to both restenosis and stent thrombosis and can be treated as described in Chapter 23: Balloon Uncrossable and Balloon Undilatable Lesions , Section 23.2 on balloon undilatable lesions.
Coronary brachytherapy ( Section 30 ) is an additional treatment option for recurrent in-stent restenosis. Beta-radiation is administered within the restenosed coronary segment to reduce the risk of restenosis. Indefinite dual antiplatelet therapy is required afterwards due to increased risk of stent thrombosis.
22.2.10
Stenting
Stent thrombosis: repeat stenting may be needed if a suboptimal result is obtained after PCI of the stent thrombosis lesion.
In-stent restenosis: the first episode of in-stent restenosis is typically treated with repeat DES implantation, after confirming that the lesion is well dilated. Recurrent in-stent restenosis is best treated with brachytherapy or drug-coated balloons (which are not currently available in the United States) ( Section 30.9.6 ).
If the mechanism of stent occlusion is stent undersizing or underexpansion ( Section 23.2 ), intravascular imaging is critical for stent sizing and assessment of expansion of the new stent. High-pressure postdilatation with a noncompliant balloon is recommended.
If the mechanism of stent occlusion is stent fracture, a new stent is usually implanted.
If the mechanism of the stent occlusion is a gap, intravascular imaging and stent imaging enhancing technologies can help fully cover the gap and the old stent.
22.2.11
Closure
Access closure is performed as described in Chapter 11 : Access Closure.
22.2.12
Coronary physiology
Coronary physiology can help assess the significance of stent failure lesions as described in Chapter 12: Coronary Physiology , although intracoronary imaging is preferred in most cases.
22.2.13
Intravascular imaging
Intravascular imaging, is essential for stent failure cases (both stent thrombosis and in-stent restenosis). It allows determination of the mechanism of stent failure, such as neointima formation, neoatherosclerosis, stent underexpansion or stent fracture, and helps guide treatment, as described in Chapter 13: Coronary Intravascular Imaging .
22.2.14
Hemodynamic support
Hemodynamic support may be needed, especially in cases of stent thrombosis, as described in Chapter 14: Hemodynamic Support .
22.3
Small and large vessels
Small (<2.5 mm) or large (≥ 4.0 mm) vessels pose additional challenges to PCI.
22.3.1
Planning
Planning is performed as described in Chapter 1: Planning .
22.3.2
Monitoring
Monitoring is performed as described in Chapter 2: Monitoring .
22.3.3
Medications
Medication administration is similar to standard PCI, as described in Chapter 3: Medications .
22.3.4
Access
Radial or femoral access can be used, as described in Chapter 4: Access .
22.3.5
Engagement
Performed as described in Chapter 5: Coronary and Graft Engagement .
22.3.6
Angiography
Angiography is performed as described in Chapter 6: Coronary Angiography .
Small vessels: administration of nitroglycerin is critical in patients with small coronary arteries, to ensure that the target arteries do not appear to be small due to spasm.
Large vessels: forceful contrast injection and possibly use of a guide catheter are important for completely filling large coronary vessels.
Sometimes, large vessel size is due to a focal (coronary artery aneurysm) or diffuse (coronary artery ectasia) dilation of coronary segments to a size at least 1.5 times bigger than the adjacent normal segment .
22.3.7
Selecting target lesion(s)
Small vessels: Both PCI and CABG are more challenging in patients with small coronary arteries. Stenting of small coronary arteries carries increased risk of restenosis, especially in patients with diabetes mellitus.
22.3.8
Wiring
Small vessels: aggressive wire manipulation should be avoided to minimize the risk of vessel injury and dissection.
Large vessels: wiring side branches through large vessels, can be challenging due to guidewire prolapse. Use of polymer jacketed guidewires and angulated microcatheters can assist wiring side branches in large vessels.
22.3.9
Lesion preparation
Small vessels: Atherectomy is generally avoided in small coronary vessels, especially if they are highly tortuous. Oversized balloons should also be avoided as they can cause dissections requiring longer stent length. Drug-coated balloons can also be used in this setting .
Large vessels: Use of intravascular imaging can be very helpful for optimal selection of balloon and stent size.
22.3.10
Stenting
Small vessels: the smallest currently available stent is the 2.0 mm Resolute Onyx stent. Minimizing stent length (while covering the target lesion) may help reduce the risk of restenosis.
Large vessels: the largest diameter DES currently available is the Resolute Onyx that is available in diameters up to 5.0 mm (and can be expanded up to 5.75 mm). The 4.0 mm Synergy stent can also be expanded up to 5.75 mm and the 3.5 and 4.0 mm Xience Sierra stents can be expanded up to 5.5 mm ( Chapter 10: Stenting , Section 10.2.3 and Fig. 10.1 ). The stent diameter should be selected based on the distal reference diameter, followed by postdilation of the more proximal segment of the stent with a larger and shorter noncompliant balloon sized according to the proximal reference segment.
22.3.11
Closure
Access closure is performed as described in Chapter 11 : Access Closure.
22.3.12
Coronary physiology
Small vessels: coronary physiology can be very helpful in determining the physiologic significance of lesions, as functional assessment depends both on the severity of the stenosis and on the size of the territory supplied by this vessel.
Large vessels: assessment of lesion severity can also be challenging in large vessels, potentially benefiting from physiologic assessment.
22.3.13
Intravascular imaging
Small vessels: Intravascular imaging can help determine the true size of the target vessel and determine whether there is positive remodeling, which may enable placement of larger stents.
Large vessels: Intravascular imaging can help accurately determine the true size of the vessel. IVUS is preferred over OCT, as complete vessel filling with contrast can be challenging in large vessels.
22.3.14
Hemodynamic support
Hemodynamic support may be needed, as described in Chapter 14: Hemodynamic Support .
22.4
Long lesions
22.4.1
Planning
Planning is performed as discussed in Chapter 1: Planning .
22.4.2
Monitoring
Monitoring is performed as described in Chapter 2: Monitoring .
22.4.3
Medications
Medication administration is similar to standard PCI, as described in Chapter 3: Medications .
22.4.4
Access
Radial or femoral access can be used, as described in Chapter 4: Access .
22.4.5
Engagement
Performed as described in Chapter 5: Coronary and Graft Engagement .
22.4.6
Angiography
Performed as descried in Chapter 6: Coronary Angiography .
22.4.7
Selecting target lesion(s)
The presence of long coronary lesions is associated with increased risk of restenosis after stenting, which should be taken into account before deciding on the type (PCI vs CABG) of coronary revascularization.
22.4.8
Wiring
Performed as described in Chapter 8: Wiring . Aggressive wire manipulation should be avoided to reduce the risk of dissection or vessel injury.
22.4.9
Lesion preparation
Performed as described in Chapter 9: Lesion Preparation .
22.4.10
Stenting
The longest stent available in the United States is currently 40 mm (Orsiro, Biotronik). Hence, multiple stents may be needed for stenting long coronary lesions, such as chronic total occlusions.
22.4.11
Closure
Access closure is performed as described in Chapter 11 : Access Closure.
22.4.12
Coronary physiology
Coronary physiology can help determine the location of the stenosis by doing a pullback: the presence of a step-up may suggest that the lesion is more focal than apparent by angiography.
22.4.13
Intravascular imaging
Intravascular imaging can facilitate treatment of long coronary lesions that have higher risk of restenosis, by accurately measuring the proximal and distal reference vessel diameter and the lesion length. IVUS-guided PCI of long lesions (≥28 mm in length) was associated with lower incidence of subsequent major adverse cardiac events compared with angiography-only guided PCI in the IVUS-XPL trial .
22.4.14
Hemodynamic support
Hemodynamic support may be needed, as discussed in Chapter 14: Hemodynamic Support .
References
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