Examination Medicine: A Guide to Physician Training (11 page)

c. 
There is now trial evidence that transport of patients to a hospital where this procedure can be performed is preferable to treatment with thrombolytic drugs, if transport time is less than 2–3 hours.

d. 
Rapid transport to the catheter laboratory is important and the ‘door to balloon’ time should be less than 90 minutes when angioplasty is available in the hospital to which the patient presented.

3. 
If the history has suggested complications resulting from the infarct, these will have to be discussed. Common complications include:

•
 
ventricular arrhythmias

•
 
bradyarrhythmias (especially following an inferior infarct)

•
 
cardiac failure

•
 
further ischaemia or reinfarction.

It is important to have planned an approach to the management of these problems.

Investigations

These are aimed at assessment of the infarct size, complications and presence of further ischaemia:

1. 
left ventricular function
– echocardiogram, left ventriculogram

2. 
complications
– echocardiogram for valvular regurgitation, left ventricular thrombus, infarct-related VSD

3. 
further ischaemia
– exercise test, sestamibi stress test, cardiac catheterisation

4. 
viability
– MRI scan, sestamibi scan.

Long-term treatment

1. 
Early revascularisation is of proven benefit for high-risk patients with acute coronary syndromes (ST elevation, troponin elevation).

2. 
Prognosis is improved with aspirin, beta-blockers and, for large infarcts (ejection fraction <40%), ACE inhibitors and beta-blockers (e.g. carvedilol, bisoprolol and extended-release metoprolol).

3. 
Patients with three-vessel disease and significant left ventricular damage or with left main coronary artery stenosis benefit prognostically from coronary artery bypass surgery even if their symptoms have settled on medical treatment. Those with tight proximal (before the first diagonal branch) left anterior descending lesions probably also benefit from surgery or angioplasty.

4. 
Epleronone, an aldosterone antagonist, is indicated for patients with cardiac failure following an infarct.

Secondary prevention

1. 
Control of cardiac risk factors is even more important once the presence of coronary artery disease has been established. It should be a routine part of the management of these patients.

2. 
Dietary advice for weight and lipid reduction may be indicated. Lipid-lowering drug treatment with a statin should be introduced for all patients who can tolerate it. Total cholesterol should be reduced to less than 4.0 mmol/L (aim for the LDL to be below 1.8 mmol/L).

3. 
Patients should be encouraged to take part in a cardiac rehabilitation program, if this is available, where advice about safe exercise, weight reduction and changes to dietary and smoking habits can be encouraged.

Revascularisation

For some long-case patients with ischaemic heart disease the emphasis will be on revascularisation (coronary surgery or angioplasty). These procedures are so common that many patients with other presenting problems will have had them.

The history

Similar information to that outlined in the ischaemic heart disease long case is required.

1. 
Careful questioning about risk factor control, both before and after surgery or angioplasty, is very important. The patient should know whether he or she has ever had an infarct and may know whether there was significant left ventricular damage.

2. 
Find out what procedure (or procedures) the patient has had and whether there has been complete relief of symptoms.

3. 
If coronary artery surgery was performed, ask how many grafts were inserted and whether internal mammary or other arterial (e.g. radial artery) conduits were used. It may be possible from the history to work out whether surgery was performed to improve symptoms or prognosis (e.g. three-vessel or left main disease), or both.

4. 
The patient may know how many vessels were dilated if angioplasty was performed and whether stents were inserted. The patient should know whether bare metal stents (BMS) or drug-eluting stents were used. Ask whether the angioplasty was performed in the setting of a myocardial infarction or acute coronary syndrome. Find out for how long dual anti-platelet treatment was prescribed.

The examination

Examine the patient as for the ischaemic heart disease long case.

1. 
Note the presence of a median sternotomy scar. Patients who have had a left internal mammary artery (LIMA) graft often have a numb patch to the left of the sternum. This may be permanent.

2. 
Look at the sternal wound for signs of infection; osteomyelitis of the sternum is a rare but disastrous complication of surgery. Look and feel for sternal instability. Sternal wires are often palpable.

3. 
Examine the arms for the very large scar that results from radial artery harvesting.

4. 
Examine the legs for saphenous vein harvesting wounds. Infection and breakdown of these wounds are more common than for the sternal wound.

Management

SURGERY

Use of the left internal mammary artery to graft the left anterior descending (LAD) coronary artery has been routine for more than 20 years. Other arterial conduits are used less often, but ‘all arterial revascularisation’ is performed routinely in some centres or where saphenous vein grafts (SVGs) are not possible, e.g. previous coronary artery bypass graft (CABG) or varicose veins in both legs and thighs. In these cases the right internal mammary artery (RIMA) may be used, usually to graft the right coronary, or the radial artery is used as a free arterial graft. The RIMA may also be used as a free graft attached to the aorta, if that is necessary to make it reach. There is excellent evidence that left internal mammary artery (LIMA) grafts have a higher long-term patency rate (>90% at 10 years) than SVGs (50% at 10 years). There is less information about other arterial conduits.

In response to the increasing numbers of angioplasty procedures, surgeons have begun to perform fewer invasive bypass procedures. The most widely used alternative is the ‘off-pump’ LIMA graft to the LAD coronary artery. A median sternotomy incision is still used, but the LIMA is attached to the LAD coronary artery on the beating heart.
A ‘Y’ graft from the LIMA to the circumflex and right coronaries can be performed using the RIMA attached to the LIMA. These operations avoid the need for cardiopulmonary bypass, speed recovery and possibly reduce the risk of intraoperative cerebral events. Minimally invasive bypasses are carried out in some centres. A series of lateral chest incisions are used as ports for surgery using thoracoscopic equipment. The technique is not easy and the chest wound, although small, is not necessarily less painful than a median sternotomy.

Angina may recur at any time after CABG. Very early angina suggests a technical problem, such as mammary artery spasm, thrombosis of an SVG, grafting of the wrong vessel or grafting of the correct vessel, but proximal to the area of stenosis. Sometimes revascularisation may be ‘incomplete’ because one or more vessels were unsuitable for grafting – usually because of distal disease in the target vessel.

Recurrence of angina is more common if risk factors have not been aggressively controlled. Low-dose aspirin has also been shown to prolong graft survival. When angina recurs the patient usually describes symptoms similar in character to the old ones. Recurrent chest pain that is different from the old angina is less likely to be ischaemic.

ANGIOPLASTY

Angioplasty is now performed more often than surgery in many centres. It has not been shown to improve the prognosis for patients with stable angina (COURAGE trial). A number of studies have shown a similar outcome to surgery in patients with three-vessel disease, but at the expense of a higher number of repeat procedures. Diabetics were a subgroup with a worse outcome from angioplasty than from surgery.

Many angioplasties are performed to provide symptom relief for patients with one- or two-vessel disease. Increasingly, however, patients with acute coronary syndromes, and especially those with raised troponin levels, are treated with early angioplasty. There is now good evidence that this group of patients has an improved prognosis (fewer deaths and fewer large infarcts) and a shortened hospital stay when treated aggressively with angioplasty.

The majority (>90%) of dilated vessels are now stented, which has made a considerable difference to the risk of acute closure of the artery or the need for urgent surgery (now a rare event). It has also reduced the clinical restenosis rate (i.e. recurrence of symptoms and angiographic evidence of >50% loss of luminal diameter) from almost 40% to 10%.

Dual anti-platelet treatment with aspirin and clopidogrel or prasugrel has made subacute stent thrombosis a rare event (<1%). Clopidogrel is ideally given for 48 hours before angioplasty and for at least 4 weeks afterwards; 6 months to a year is often recommended for patients who have had an acute coronary syndrome.

For patients treated for an infarct or acute coronary syndrome, a loading dose of 300–600 mg of clopidogrel is given (60 mg of prasugrel), and 6 months to a year of dual anti-platelet treatment is often recommended.

If a drug-eluting stent is used, 1 year or more of dual-platelet treatment is now recommended because of concerns about delayed healing and a risk of late stent thrombosis (about 1% per year). Patients should continue with aspirin forever.

For some primary angioplasties or complicated angioplasties (large dissection or large burden of thrombus), the potent platelet aggregation inhibitor abciximab (a receptor antibody) may be used as a bolus, followed by infusion for some hours. This drug is very effective in preventing closure of the vessel, but is expensive. Abciximab and tirofiban (a small molecule platelet aggregation inhibitor) are very valuable drugs for the management of acute coronary syndromes with angioplasty. Tirofiban has a shorter half-life than abciximab, but should be used for at least 24–48 hours before intervention, unless it is started in the catheter laboratory with a double bolus dose.

Primary angioplasty of the infarct-related artery is the recommended treatment for STEMI if it can be performed in an experienced centre and if there will not be more than 90 minutes additional delay compared with the use of thrombolytic treatment. It results in a lower mortality and shortened hospital stay.

The ‘open artery hypothesis’ suggests that having a patent artery after an infarct is an advantage (possibly because of its effects on remodelling). For this reason occluded arteries may be opened and dilated even late after an infarct, especially if the patient has evidence of persisting ischaemia. However, the Open Artery Trial (OAT) did not show benefit when routine re-opening of the infarct-related artery was performed more than 48 hours after the infarct in the absence of evidence of ischaemia.

Restenosis remains a problem after angioplasty. It is very unusual after 6 months. It is more common in diabetics, in calcified and complex and long lesions, and in dilated vein grafts. A combination of these factors can result in a restenosis rate of more than 60%. Treatment is usually by redilatation and insertion of a drug-eluting stent. Dilatation with a drug coated balloon is a newer option.

Drug-eluting stents have dramatically reduced the incidence of restenosis. The currently available stents have either paclitaxel, everolimus or sirolimus bound via a polymer to the metal surface of the stent. These antineoplastic drugs are eluted for about a month and prevent the migration of smooth muscle cells into the lumen of the vessel that is the cause of restenosis. Very low restenosis rates of a few per cent have been obtained in trials, even when diabetics are included. These stents also seem to be effective in preventing further restenosis when used in a restenosed bare metal stent. Drug-eluting stents are very expensive – about four times the cost of bare metal stents – and the usual indications for their use include long lesions in small vessels, redilatation of restenosis and diabetes. They are not used for patients who may need a surgical procedure within the following 6 months to a year because of the risk of stopping anti-platelet treatment during this period.

Stents do not set off metal detectors and patients can safely have an MRI scan within a month.

Infective endocarditis

Patients with infective endocarditis stay in hospital for weeks, so they are often available for long cases. The disease presents diagnostic, plus short-term and long-term management problems. Cases combine cardiological, microbiological and immunological problems. The diagnosis is usually known to the patient. An intravenous infusion containing antibiotics is a valuable clue.

The history

Ask about:

1. 
details of presenting symptoms (e.g. malaise, fever, symptoms of anaemia)

2. 
symptoms suggesting embolic phenomena to large vessels (e.g. brain, viscera) or small vessels (e.g. kidney, with haematuria or loin pain)

3. 
recent dental, endoscopic or operative procedures – a precipitating event is identified in only about 5% of cases (the time between procedure and diagnosis may be up to 3 months); remember that
Streptococcus bovis
or
Clostridium septicus
endocarditis is associated with colonic cancer and these patients all deserve a colonoscopy!

4. 
use of antibiotics for prophylaxis, either before an invasive procedure or for rheumatic fever, or both

5. 
a past history of rheumatic fever