CARDIOLOGY DOCTORS IN BANNERGHTTA ROAD
ST elevation myocardial infarction
Modern treatment of myocardial infarction has made a profound difference to the prognosis
of this life-threatening condition. Before the introduction of CCUs, the expected in-hospital
mortality of this condition was more than 20%. Monitoring and treatment of arrhythmias, and
correction of biochemical and, where possible, haemodynamic complications in CCUs reduced
this to about 12%. The ‘thrombolytic era’, which began with the publication of the results of
the GISSI Trial, 31 has dramatically changed the approach to the management of infarction. The
use of thrombolytic drugs (streptokinase in GISSI) reduced mortality to less than 10%, with
greater benefit for those treated early.32 The addition of aspirin in later trials reduced mortality
to about 7% and many CCUs now achieve mortality rates of 5 or 6%. There is no doubt that
early treatment makes the greatest difference, but some benefit may be seen with treatment
given up to 12 hours after the onset of symptoms of infarction.
In centres where it can be performed primary angioplasty is the reperfusion treatment
of choice for myocardial infarction. This is a grade A recommendation—level I evidence.33
rates below 5% can be achieved.
The rationale for reperfusion treatment came with the realisation that infarction was caused
by thrombosis within a coronary artery (a mechanism first proposed by Herrick in 191234) and
that restoring blood flow before irreversible damage had occurred would be helpful. It has been
known for a long time that the prognosis following myocardial infarction depends more than
anything else on the amount of left ventricular damage that has occurred.
For these reasons the early diagnosis of infarction has become very important. Patients with
symptoms suggestive of infarction should have an ECG performed as soon as possible. If nondiagnostic
changes are present, the tracing should be repeated frequently so that appropriate
early decisions about treatment can be made if changes appear.
The current ECG criteria for the use of reperfusion treatment (primary angioplasty