Classification of Braunwald for Unstable Angina

 

Unstable angina: complex condition existing between chronic stable angina and acute myocardial infarction.

 

Descriptors:

(1) severity

(2) clinical circumstances

(3) relative to therapy

Severity	Class
no pain at rest during past month; new onset of severe angina or accelerated angina	I
angina at rest within past month but not within preceding 48 hours (subacute)	II
angina at rest within past 48 hours (acute)	III

 

where:

• Class I includes new onset (< 2 months) of severe or accelerated angina. This includes (a) patients with exertional angina pectoris that is severe or frequent (>= 3 episodes per day) or (b) patients with chronic stable angina who develop accelerated angina (angina that is more frequent, severe, longer in duration or precipitated by distinctly less exertion than previously) but who have not experienced pain at rest during past 2 months.

• The description of Class I mentions no pain at rest for past 2 months, but Class II is chest pain in past month. This leaves pain at rest in 1-2 month timeframe uncovered. I changed the definition for Class I to no pain in past month accordingly.

• It might be useful to include a Class 0 for patients without pain who don't meet the criteria for Class I.

 

Clinical Circumstances	Class
secondary unstable angina	A
primary unstable angina	B
post-infarction	C

 

where:

• Secondary unstable angina occurs in the presence of an extracardiac condition that intensifies myocardial ischemia. Examples of such conditions include: anemia, fever, infection, hypotension, uncontrolled hypertension, unusual emotional stress, thyrotoxicosis, and hypoxemia (tachyarrhythmia is also listed, but this is not extracardiac).

• Primary unstable angina develops in the absence of an extracardiac condition.

• Post-infarction unstable angina develops within 2 weeks of a myocardial infarction. I wonder if there is need for a class for a person who develops the angina more than 2 weeks after an MI.

 

Therapy	Class
none	1
during therapy for chronic stable angina	2
despite maximal anti-ischemic drug therapy	3

 

classification =

= (class for severity) + (class for clinical circumstance) +/- (class for therapy)

 

NOTE: This classification was prior to availability of serum troponin measurements.

 

Modified Scheme (2000)

 

With the availability of serum troponin measures, class IIIB was subdivided into:

(1) IIIB, troponin positive

(2) IIIB, troponin negative

Risk	IIIB, troponin negative	IIIB, troponin positive
24 hour mortality or AMI	< 1%	5%
30 day mortality or AMI	< 2%	15-20%
6 month mortality or AMI	< 5%	25%

after Table 2, Hamm and Braunwald, page 120