Percutaneous Coronary Intervention

Synonyms: percutaneous transluminal coronary angioplasty (PTCA), formerly known as balloon angioplasty.

This is one of the two coronary revascularisation techniques currently used in the treatment of ischaemic heart disease¹, the other being coronary artery bypass grafting (CABG).

Percutaneous coronary intervention (PCI) involves non-surgical widening of the coronary artery, using a balloon catheter to dilate the artery from within. A metallic stent is usually placed in the artery after dilatation. Antiplatelet agents are also used. Stents may be either bare metal or drug-eluting stents (see box).

Note that indications for PCI may change as the procedures continue to be refined, and with emerging evidence.

1. ST segment elevation myocardial infarction (STEMI):²
   • When available, angioplasty with stenting is the optimal method of reperfusion for STEMI. The target "door to balloon time" is 90 minutes.
   • As rescue treatment in patients treated by thrombolysis - if there is failure to reperfuse, further ischaemia or further MI.
   • As early intervention in patients treated with thrombolysis.
2. Non-ST elevation acute coronary syndrome (NSTACS) - unstable angina and non-ST elevation myocardial infarction (NSTEMI):²
   • For patients who are at medium-to-high risk of subsequent cardiac events, offer angiogram and/or PCI before discharge. Early invasive investigation and revascularisation (compared to conservative treatment) may reduce subsequent MI and refractory angina.
3. Stable angina:¹
   • Patients with single or double vessel disease, where optimal medical therapy fails to control symptoms.
   • Patients with triple vessel disease, who are unsuitable for CABG.

• Consider the pros and cons of PCI versus optimal drug therapy and/or CABG.^3,4
• Because anti-platelet drugs are crucially important after PCI (to prevent thrombosis in the stent, see below), decisions about PCI and the type of stent used must bear in mind:^5,6
  • Is there likelihood that surgery will be needed? Consider the increased risk of bleeding with antiplatelet drugs, but risk of thrombosis if these drugs are stopped.
  • Can the patient adhere to antiplatelet treatment (and is there funding to do so)?
  • Any contra-indications to antiplatelet drugs.

• PCI should be done by experienced, high volume operators and institutions.
• No anaesthetic is needed, though patients may be given a sedative. Patients can usually mobilise a few hours afterwards, and go home the same or next day.
• The technique involves gaining arterial access via the femoral, radial or brachial arteries. Under fluoroscopy, a guidewire is passed into the coronary artery and across the stenosis; the balloon or stent catheter passed over it, and the lesion dilated and/or stented. Glycoprotein IIb/IIIa inhibitors are given in 'high-risk' procedures, and opiates may be used if angina occurs during angioplasty.

Antiplatelet drug treatment following percutaneous coronary intervention^6,9

• All patients should take aspirin indefinitely (as secondary prevention of CVD).
• 'Dual antiplatelet therapy' is required for patients with coronary stents to reduce the risk of stent thrombosis:
  • This normally comprises aspirin and clopidogrel. The duration of clopidogrel treatment depends on the clinical setting, but current recommendations are usually:
    • For BMSs, clopidogrel for at least one month.
    • For DESs, clopidogrel for at least 12 months. Some cardiologists feel that clopidogrel should be continued indefinitely.
• Antiplatelet agents should not be stopped, and patients are advised to carry a warning card. Cards are available from the UK Clinical Pharmacy Association (admin@ukcpa.com).¹⁰
• If surgery is required, consider whether the antiplatelet drugs can be continued; consult with cardiologist as to the risks of discontinuing these drugs and any necessary precautions.⁹
• The use of proton-pump inhibitors together with clopidogrel (to prevent gastric bleeding) is controversial, after evidence suggesting that PPIs may worsen outcomes, and that the two drugs may interact.

Driving¹¹

After elective PCI:

• Group 1 licence - stop driving for 1 week; can recommence thereafter if there is no other disqualifying condition. DVLA need not be notified.
• Group 2 license - stop driving for at least 6 weeks. Re-licensing may be permitted thereafter provided that other functional test requirements can be met and there is no other disqualifying condition.

• Stent thrombosis:
  • This is a risk until the stent becomes covered by endothelium.
  • Usually presents as acute MI, with a high mortality.
  • Is most frequent during the first month, but can occur months or years after the PCI.
  • Occurs in 1-2% of patients.
• Restenosis of the stent:
  • This is due to excessive 'healing' of the vessel wall, which encroaches on the stent lumen.
  • Typically, it develops within 3-6 months.
  • Presents as a return of angina; rarely causes MI.
  • Occurs in 4-20% of stents.
• Other major complications are uncommon, but include: death (0.2% but higher in high-risk cases), acute MI (1%) which may require emergency CABG, stroke (0.5%), cardiac tamponade (0.5%) and systemic bleeding (0.5%).
• Minor complications are: allergy to the contrast medium, nephropathy and complications at the access site, such as bleeding and haematoma.

• Bioabsorbable stents are being trialled and have potential advantages.¹²
• Triple antiplatelet therapy may be beneficial.¹³
• New anti-thrombotic drugs, such as thrombin receptor (protease activated receptor-1 (PAR-1)) antagonists might reduce thrombosis without affecting haemostasis.¹⁴