Complications of percutaneous coronary interventions

Preprocedural planning and risk prediction

Previously, operators in the catheterization (cath) lab attempted to improve outcomes by decreasing access-related complications—mainly by moving toward smaller French (F) sized sheaths and eventually by embracing radial artery catheterizations. Over the past years, the cath lab environment has changed with more widespread adoption of PCI for chronic total occlusions (CTOs) and large-bore femoral access for the insertion of mechanical support devices to support higher-risk and challenging PCI procedures. In taking on these higher-complexity procedures, increasing complications (numerically) logically follow. Therefore it may be worth understanding the contributors to mortality associated with “modern” PCI.

A recent review of PCI procedures revealed that the factors most strongly associated with mortality were salvage PCI procedures, patients in refractory shock, or those undergoing PCI while in cardiogenic shock ( Fig 12.1A ). Nevertheless, emergency PCI in patients without shock was also strongly associated with mortality, as was PCI performed in patients with advanced chronic kidney disease. As noted in Fig. 12.1B , most of the mortality after PCI is isolated in those at the highest risk. The Society for Cardiovascular Angiography and Interventions (SCAI) also has a risk calculator that can inform treating physicians about procedural risk ( http://scaipciriskapp.org/porc ).

All patients who present for PCI with a higher risk for mortality should have a documented discussion with the institution’s “Heart Team” (consisting of cardiac surgery, interventional cardiology, and the treating physician[s]) regarding the nuances of proceeding with a catheter-based procedure despite higher risk. Furthermore, the patient, the patient’s family, and all the team members in the cath lab should be fully aware of this discussion and the risk of the procedure before proceeding.

Complications

As previously stated, complications in the cath lab remain a rare occurrence, and this creates a barrier to prompt recognition and potential treatment because most in the lab will not have the benefit of experience in complication recognition. Some have advocated for “protocolized” thinking when overall experiential knowledge has difficulty guiding decision making. One such protocol was put together by a group of experienced operators to go through the “basic” steps when a complication is suspected ( Fig. 12.2 ). The key aspect to this flow chart is the importance of assessing the hemodynamic stability of the patient and calling for help early.

To ensure as much preparedness for complications and emergent scenarios as possible, labs should consider conducting “mock” events—practicing the steps needed to deal with potentially catastrophic emergencies and having team members perform their defined roles during the emergency on a regular basis. Furthermore, Box 12.1 outlines equipment and resources that every lab should make sure that they have accounted for before performing any PCI.

Vascular access

The first part of any PCI begins with vascular access. Using the femoral access, the major complications are femoral artery dissections ( Fig. 12.3 ), pseudoaneurysm, arteriovenous (AV) fistula, and retroperitoneal bleeding. As seen in Table 12.1 , the incidence of these complications is increased compared with a strictly diagnostic procedure. All arterial complications are markedly reduced (but are not eliminated) using the radial artery access.

Femoral access complications

Pseudo-aneurysm

Often associated with a low puncture, a femoral artery pseudoaneurysm represents a failure of sealing of the initial arterial puncture site, allowing arterial blood to flow into the surrounding tissue. This forms a pulsatile hematoma that acts as the covering roof over the aneurysm (see Fig. 12.3 ). Pseudoaneurysms are late appearing, associated with local pain and swelling, and diagnosed with femoral ultrasound with an excellent sensitivity of 94% to 97%. There are multiple risk factors for pseudoaneurysm ( Box 12.2 ).

Box 12.2

Risk Factors for Pseudoaneurysm Formation

Procedural factors

• Catheterization of both artery and vein

  • Cannulation of the superficial femoral or profunda femoris rather than common femoral

  • Inadequate compression after procedure

  • More anticoagulation used

Patient factors

• Obesity

  • Hemodialysis

  • Calcified arteries

Small pseudoaneurysms (<2 cm) often close spontaneously within 1 month. In larger pseudoaneurysms, or in small ones that fail to close, active treatment is necessary. The two most common treatment methods are ultrasound-guided compression or thrombin injection. In some hospitals, ultrasound-guided compression is not offered because of increased stress-related wrist injury to the ultrasound technician. Other advantages of thrombin injection over ultrasound compression are seen in Box 12.3 .

Box 12.3

Advantages of Thrombin Injection Compared With Ultrasound Compression for Management of Pseudoaneurysm

• Greater technical success (96% vs. 74%)

  • Less painful to the patient and technician

  • No conscious sedation required

  • Effective in patients on anticoagulation

  • Can be used in pseudoaneurysms above the inguinal ligament

Thrombin injection can be performed by diluting 1000 U thrombin in a 1-mL syringe with normal saline (final concentration of 100 U per 0.1 mL) and injecting with direct ultrasound visualization through a long 22-gauge needle until thrombus is formed in the pseudoaneurysm cavity and Doppler-detected flow is abolished ( Fig. 12.4 ). Rarely, in very large pseudoaneurysms and those resistant to thrombin injection, vascular surgery is required.

Arteriovenous fistula

Another complication of vascular access is a femoral AV fistula formation (see Fig. 12.4 ). This is recognized on physical examination by a palpable thrill or an audible continuous bruit. Unlike pseudoaneurysms, conservative treatment with watchful waiting is the most common treatment modality (90%), which is likely related to the fact that AV fistulae produce low shunt blood flow volumes (160–510 mL/min) compared with most large intracardiac (e.g., left to right) shunts or dialysis shunts (1000 mL/min). One-third of persistent AV fistulae will close during the first 12 months. Most persistent AV fistulae are asymptomatic and do not require repair. Rarely, they can be symptomatic (moderate pain) and, in large patient series, about 10% of AV fistulae will ultimately require surgical repair. AV shunt flows must exceed 30% of the cardiac output to produce symptoms, and therefore it is quite rare to have a truly symptomatic shunt from a femoral AV fistula. The main risk factor for development of an AV fistula is a low femoral arterial puncture, which is responsible for almost 85% of all AV fistulae.