Classification of Unstable Angina
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 - High risk features include ongoing chest pain, pulmonary edema, dynamic ST
   segment changes, hypotension, S3 or rales.  Intermediate risk features
   include rest angina (> 20 min), nocturnal angina, dynamic T wave changes, Q
   waves or ST depression, angina that results in marked to severe limitations
   of physical activity or age > 65 years. Low risk features imply that no
   high or intermediate risks are present and include patients with angina of
   increased frequency, severity or duration, angina provoked at a lower
   threshold, new onset angina ( 2 weeks to 2 months) and the presence of
   normal OR unchanged ECG
   <C-AHCPR.TXT>
 - [Rizik DG, Healy S, Margulis A, Vandam D, Bakalyar D, Timmis G, Grines C,
   O'Neill WW, Schreiber TL. A new clinical classification for hospital
   prognosis of unstable angina pectoris. Am J Cardiol 1995 May
   15;75(15):993-7.]
   Abstract: <C-AngA.TXT -Rizik>
  class IA, acceleration of previous exertional angina without
    electrocardiographic (ECG) changes
  class IB, acceleration of previous exertional angina with ECG changes
  class II, new-onset exertional angina
  class III, new-onset rest angina
  class IV, protracted rest angina with ECG changes.
 - [Chahine RA. Unstable angina. The problem of definition. Br Heart J
   1975;37(12):1246-9.]
  Type I:
   (A) Patients with known chronic angina and sudden or accelerated
       progression of symptoms;
   (B) patients with chronic angina and onset of recurrent attacks at rest
   (C) patients with angina of recent onset and rapid progression into a
       severe condition.
  Type II: Severe unstable angina.  Any of the subgroups described under
           unstable angina Type I will qualify for this classification if the
           patient develops recurrent episodes of prolonged ischaemic chest
           pains resistant to nitroglycerin lasting for 15 minutes or more.