Unstable angina / non ST elevation myocardial infarction risk stratification and prognosis


 * Associate Editor-In-Chief:

Risk Stratification of the Patient with Unstable Angina Pectoris
There are several scoring systems which have been devised as methods of identifying high-risk patients presenting with acute coronary syndrome (ACS). These include, among others, the Braunwald classification system, the Rizik classification system, the TIMI risk score, the GRACE risk score and the PURSUIT risk score.

TIMI Risk Score
The TIMI Risk Score for UA/non-ST-elevation myocardial infarction (NSTEMI) is based on the TIMI 11B and ESSENCE trials and has been shown to be predictive of all-cause mortality, myocardial infarction, and severe recurrent myocardial ischemia prompting urgent revascularization for the first 14 days after presentation. It has also been validated as a tool for 30-day risk stratification of patients presenting to the emergency room with chest pain. It is very likely the most commonly used tool for risk-stratification as it is the easiest to understand and use of those listed.

The TIMI risk score is determined by the sum of the presence of 7 variables at admission; 1 point is given for each of the following variables:


 * Age 65 years or older
 * At least 3 risk factors for coronary artery disease
 * Prior coronary artery stenosis of 50% or more
 * ST segment deviation on EKG presentation
 * At least 2 anginal events in prior 24 h
 * Use of aspirin in prior 7 days
 * Elevated serum levels of cardiac biomarkers

In TIMI risk scoring, prior coronary stenosis of 50% or more remained relatively insensitive to missing information and remained a significant predictor of events.

Incidence of Adverse Events (all-cause mortality, myocardial infarction, and severe recurrent myocardial ischemia prompting urgent revascularization for the first 14 days after presentation)


 * TIMI Risk Score 0/1: 4.7%
 * TIMI Risk Score 2: 8.3%
 * TIMI Risk Score 3: 13.2%
 * TIMI Risk Score 4: 19.9%
 * TIMI Risk Score 5: 26.2%
 * TIMI Risk Score 6/7: 40.9%

Braunwald Classification
The Braunwald Classification of unstable angina pectoris (UAP) stratifies patients according to both the type of anginal pain and the underlying cause of the pain. Increasing class is associated with increasing risk of both recurrent ischemia and death at 6 months.

Characteristics

 * Class I: Exertional angina (new onset, severe, or accelerated; angina of less than 2 months duration; more frequent angina; angina precipitated by less exertion; no rest angina in the last 2 months)
 * Class II: Rest angina, subacute (rest angina within the last month but none within 48 hours of presentation)
 * Class III: Rest angina, acute (rest angina within 48 hours of presentation)

Clinical Circumstances

 * Class A: Secondary unstable angina (caused by a noncardiac condition such as anemia, infection, thyrotoxicosis or hypoxemia)
 * Class B: Primary unstable angina
 * Class C: Post-infarction unstable angina (within 2 weeks of documented myocardial infarction)

Rizik Classification Scheme
The Rizik classification scheme of UAP has been shown to be predictive of in-hospital adverse cardiac events and as such could be used to make decisions regarding hospitalization and intensity of treatment.


 * Class IA: Acceleration of previously existent chronic stable angina without new EKG changes
 * Class IB: Acceleration of previously existent chronic stable angina with new EKG changes
 * Class II: Exertional angina of new onset without respect to EKG morphology
 * Class III: New onset resting angina (either with or without history of prior stable angina)
 * Class IV: Patients with protracted chest pain of > 20 minutes with EKG changes

The PURSUIT Risk Score
The PURSUIT Risk score has been shown to be predictive of the 30-day incidence of death and the composite of death or myocardial (re)infarction in patients presenting with UA/NSTEMI (patients with ACS but without ST-elevation myocardial infarction). Points are given for each of the 7 below risk factors. The points are then summed to provide a risk score which can then be converted to a probability of either death or a composite of death or MI (from 0% to 50% depending on total points).


 * Age (increased probability for age above 60 and above)
 * Gender (increased probability for men, no increased probability for women)
 * Worst Canadian Cardiovascular Society Classification for angina pectoris in the previous 6 weeks (from angina only during very strenuous activity (Class I) to angina at rest (Class IV), increased probability for Class III or IV)
 * Heart rate (increased probability for heart rate 100 and above)
 * Systolic blood pressure (increased probability for systolic blood pressure 100 and below)
 * Signs of heart failure (i.e., rales)
 * ST-segment depression on presenting EKG

GRACE risk models
The GRACE model has been shown to be predictive of in-hospital mortality for patients presenting with ACS. The 8 risk factors listed below were shown to be the most strongly predictive. A probability of in-hospital death can be assigned by adding up the points allocated for each risk factor (range from <0.2% for less than 61 points to > 51% for more than 249 points). This model was validated as a tool to predict 6-month mortality in patients who survived hospital admission for ACS as well.


 * Increasing age (0-100 points)
 * Increasing Killip class (0-59 points)
 * Decreasing systolic blood pressure (0-58 points)
 * ST-segment deviation (28 points)
 * Cardiac arrest during presentation (39 points)
 * Increasing serum creatinine level (1-28 points)
 * Elevated initial cardiac enzymes (14 points)
 * Increasing heart rate (0-46 points)