CCARDIOLOGIST IN DODDABOMMASANDRA, BANGALORE
A detailed drug history is essential. Ask about anti-anginal and anti-failure drugs. It is important
to attempt to ensure that the patient gets these drugs on the day of the operation. This applies
most of all to beta-blockers. Withdrawal of beta-blockers used for angina can precipitate unstable
angina or an infarct. There is also evidence that the use of beta-blockers in the peri-operative
period reduces the risk of significant ischaemic events.36 This is probably not the case for nitrates
and calcium antagonists.
Aspirin used for any patient with ischaemic heart disease should be stopped for the shortest
possible period before surgery (about three days) .
Warfarin, when used for protection against embolic events for atrial fibrillation, can usually
be stopped four or five days pre-op and begun again soon afterwards. A possible exception is a
patient with atrial fibrillation and a recent embolic event or a left atrial thrombus seen on echo.
These patients may need to change to heparin, as detailed below.
A history of infective endocarditis, known valvular heart disease (even if mild) or the
presence of a prosthetic cardiac valve may be an indication for antibiotic prophylaxis. Patients
with a prosthetic heart valve who are taking warfarin need careful management. If the valve
is in the aortic position and it is a modern disc valve, it may be safe to allow the INR to fall
moderately (to 1.8 or so) by the day of surgery and then to resume warfarin as soon as the
patient can swallow. If the surgeon requires the INR to have fallen to normal or the patient
has a valve in the mitral position, then cessation of warfarin and use of heparin is necessary.
Normally the patient omits a warfarin dose and then is admitted to hospital three or four
days before surgery. Intravenous heparin is begun and the APPT adjusted to 2 or 2.5 times
normal. The heparin is stopped some hours before surgery and begun as soon afterwards as
the surgeon allows.
It is now possible, however, to use low molecular weight heparin instead