Table 1. Three principal presentations of unstable angina

Rest angina         Angina occurring at
                    rest and usually
                    prolonged >20 minutes
                    occurring within a
                    week of presentation.

New onset angina    Angina of at least
                    CCSC III severity with
                    onset within 2 months
                    of initial
                    presentation.

Increasing angina   Previously diagnosed
                    angina that is
                    distinctly more
                    frequent, longer in
                    duration, or lower in
                    threshold (i.e.,
                    increased by at least
                    one CCSC class within
                    2 months of initial
                    presentation to at
                    least CCSC III
                    severity).

Note: CCSC = Canadian Cardiovascular Society classification.