michael s
(Michael S)
#1
21 What are the risks of myocardial infarction and
death in someone with unstable angina during
hospital admission, at six months and one year?
Diana Holdright
The risks of myocardial infarction (MI) and death following the
diagnosis of unstable angina (UA) depend on the accuracy of the
diagnosis. Braunwald’s classification categorises patients
according to the severity of the pain (new onset/accelerated and
pain at rest, either within the last 48 hours or >48 hours) and to
the clinical circumstances (primary, secondary (e.g. to anaemia)
and post-infarction). Using this classification, one study showed
an in-hospital AMI/death rate of 11% for patients with rest pain
within the last 48 hours, 4% for patients with rest pain >48 hours
previously and 4% for patients with new onset/accelerated
angina.^1 The in-hospital AMI/death rate was markedly raised in
patients with post-infarct angina (46%) compared with patients
with “primary” unstable angina.
The event rate is highest at and shortly following presentation,
falling off rapidly in the first few months to a level similar to
stable angina patients after one year. Patients with new onset
angina have a better prognosis than those with acceleration of
previously stable angina or patients with rest pain. Patients with
accelerated or crescendo angina have an in-hospital mortality of
2-8% and a 1 year survival of 90%. Although patients with non-
Q wave MI, also considered within the umbrella term UA, have a
more benign in-hospital course than Q-wave MI patients, they
have higher readmission, reinfarction and revascularisation rates
subsequently. Infarct extension in-hospital is associated with a
far worse prognosis in non-Q wave MI (43% mortality, vs 15% in
Q wave MI). The following are also associated with a worse prog-
nosis in unstable angina: ST segment deviation on the ECG (but
not T wave changes), elevated cardiac enzymes, transient
myocardial ischaemia on Holter monitoring, an abnormal pre-
discharge exercise test, extensive coronary artery disease and
impaired left ventricular function.
The OASIS registry,^2 gave 7 day death/MI rates of 3.7–5.6%
and 6 month rates of 8.8–11.9%. Similarly, the VANQWISH trial^3
gave the following rates of death/non-fatal MI: 3.2–7% at hospital
discharge, 5.7–10.3% at 1 month and 18.6–24% at 1 year.
