Investigation, workup and patient preparation before PCI

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Chapter 4 Investigation, workup and patient preparation before PCI

IAN R. STARKEY

KEY POINTS

No matter how urgent the clinical situation, it is essential that certain preliminaries be observed prior to performing a PCI procedure.

Basic essentials can be summarised under the general headings of:

Oreliminary investigations;

Therapeutic alterations;

Consent; and

Anticipation (and possible prevention) of problems (PTCA).

INTRODUCTION

In 2006, nearly 74,000 PCI procedures were performed in 91 centres in the UK, a rate of just over 1200 per million population (British Cardiovascular Intervention Society [BCIS] annual survey – unpublished data). PCI has now overtaken CABG as the commonest form of myocardial revascularisation procedure performed on patients with obstructive coronary artery disease. It is important to remember that such procedures, while ‘routine’ for some operators and exciting for others, may be frightening, painful and dangerous for the patients on whom they are performed, even though statistically the success rate is high. Before such a procedure begins, much can be done to diminish the patient’s fear and pain, minimise the danger and increase further the likelihood of procedural and clinical success. The essential components of this preparation are:

P preliminary investigations;

T therapeutics;

C consent; and

A anticipation (of possible complications).

There is inevitably some overlap between these elements, all of which require consideration in all patients. The emergency nature of some procedures (e.g. primary PCI for a patient with an acute ST-elevation myocardial infarction) may curtail the time available for preparation of the patient, but should never result in omission of the basic essentials.

PRELIMINARY INVESTIGATIONS

These are needed to allow three questions to be answered:

1. Is percutaneous coronary intervention (PCI) appropriate for this patient?

With few exceptions, PCI should only be considered in a patient with symptoms of coronary artery disease, objective evidence of myocardial ischaemia/infarction and an anatomically suitable lesion(s), as demonstrated by coronary angiography. As a preliminary to such a procedure, therefore, the interventional cardiologist should review the patient’s history and the results of any non-invasive and invasive investigations. While all this information should be available in advance of procedures performed electively, it is now increasingly common that patients, especially those with acute coronary syndromes (ACS: unstable angina or acute myocardial infarction), have combined diagnostic (i.e. coronary angiography) and therapeutic (i.e. PCI) procedures performed. In this situation, it is especially important for the interventional cardiologist to retain a capacity for objective judgement, so that, for instance, a patient who might best be treated surgically does not receive sub-optimal treatment simply because it is ‘convenient’ and it has been scheduled.

2. If PCI is appropriate, is the patient fit for the procedure?

Before arrival in the cardiac catheterisation laboratory, every patient should have a clinical history documented and a physical examination performed (Fig. 4.1). These should be supplemented by some basic investigations, although the number of these will be kept to a minimum in emergency situations (Table 4.1).

Figure 4.1 History and examination of patient prior to PCI.

TABLE 4.1 INVESTIGATIONS PRIOR TO PCI

ALL PATIENTS

Full blood count

Blood urea, creatinine and electrolytes

12-lead ECG

Blood group and save

SOME PATIENTS

INR (patients on warfarin)

Chest X-ray (if clinically indicated)

Others (respiratory function tests, plasma glucose, etc. according to clinical indication)

It is of particular importance to discover conditions that might increase the technical difficulty or risk of an invasive cardiac procedure. Some such factors can be corrected but awareness of others may lead to changes in peri-procedural drug therapy (see Therapeutics below), the information provided to the patient (see Consent below) or an ability to predict, and hopefully prevent, possible complications (see Anticipation below).

3. Can anything be done to improve his/her fitness?

This is mostly discussed in the ensuing sections of this chapter. The discovery of some intercurrent medical conditions might appropriately result in the postponement of an elective procedure. Examples would include severe anaemia (especially if this may be related to active or recent bleeding), active or suspected infection, uncontrolled hypertension and possible/definite pregnancy. On rare occasions, the discovery of serious non-cardiac disease (e.g. advanced malignancy) might lead to cancellation of a planned PCI procedure.

THERAPEUTICS (TABLE 4.2)

Anti-anginal drugs

Most patients with symptomatic coronary artery disease are taking regular anti-anginal medication, which can be continued until, and indeed, after the interventional procedure. Treatment with a long-acting nitrate and/or a calcium-channel blocker may actually be of benefit in the prevention of coronary artery spasm during/after the procedure. Although there is no convincing evidence that cholesterol-lowering therapy (e.g. statin drugs) specifically affects the short-term outcome of coronary interventional procedures, such treatment is an important part of the long-term management of patients with coronary artery disease and should, likewise, be continued.

TABLE 4.2 DRUG THERAPY PRIOR TO PCI

DRUG CLASS	ACTION REQUIRED
Oral anti-anginal drugs	Continue
Cholesterol-lowering therapy	Continue
Oral anti-platelet therapy	Ensure that aspirin has been taken
Oral anti-platelet therapy	ADMINISTER LOADING DOSE OF CLOPIDOGREL (IF NOT ALREADY PRESCRIBED)
Warfarin	Discontinue if possible
	Measure INR and correct excessive anticoagulation
	TAKE APPROPRIATE MEASURES TO AVOID HAEMORRHAGE AT VASCULAR ACCESS SITE
IV Heparin	Continue
IV Heparin	Measure ACT and consider reduced bolus dose
SC Low molecular-weight heparin	Administer last injection >12 hours prior to PCI (if possible)
GP IIb/IIIa receptor antagonists	Continue but consider the use of a reduced, weight-adjusted heparin regime
Pre-medication	If necessary, use diazepam 5–20 mg orally
Antidiabetic medication	See text
Other drug therapy	Continue unchanged