Acute Coronary Symptoms
Complications and Prognosis
Complications
Complications of ACS fall into several broad categories:1,2
- Myocardial dysfunction:
- ventricular failure
- septal or free wall rupture
- cardiogenic shock
- Electrical dysfunction:
- arrhythmias, e.g. ventricular fibrillation
- conduction defects, e.g. AV block
- Mitral valve regurgitation
- Recurrent ischaemia, including stroke
- Pericarditis
- Iatrogenic complications, e.g. bleeding.
Electrical dysfunction can occur in all types of ACS, and may manifest as ventricular or atrial tachy- or bradyarrhythmias, or conduction defects.1,3 However, significant myocardial dysfunction usually only occurs when the ischaemic area is large.1
Heart failure is an important complication of ACS that is usually a consequence of myocardial damage and left ventricular dysfunction. The Killip classification is used to risk-stratify patients following MI by assessing the severity of heart failure symptoms (see below).3
In the acute setting, mild heart failure may respond to oxygen, intravenous furosemide and nitrates.3
Prognosis
Patients presenting with ACS are at risk of death, recurrent MI or stroke, particularly in the initial period. A composite of these events is often used as the primary endpoint in clinical trials in ACS.
Approximately 50% of patients with ACS die within the first month, with about half of the deaths occurring in the first 2 hours.4 However, advances in care have led to a dramatic reduction in 1-month mortality among patients who are treated in hospital, from around 25-30% in the 1960s to less than 10% today.4,5
Clinical trials and registries have identified that the most powerful independent clinical predictors of early mortality in ACS are older age, higher Killip class, elevated heart rate, lower systolic blood pressure, and anterior location of theinfarct.4 Other important predictors include a history of infarction, height, time to treatment, diabetes, weight and smoking status.6
The calculation of TIMI risk scores is useful in determining risk of death in patients with NSTE-ACS (Table 1 and Figure 1) and STEMI (Table 2 and Figure 2).3,7
| Risk Factor | Score |
|---|---|
| Age >65 years |
1 |
| >3 risk factors for coronary artery disease (hypertension, hyperlipidaemia, family history, diabetes, smoking) |
1 |
| Prior coronary stenosis of =50% |
1 |
| Aspirin use in last 7 days |
1 |
| >2 episodes of anginal pain at rest in the last 24 hours |
1 |
| Elevated serum cardiac markers |
1 |
| ST-segment deviation (elevation or depression) at presentation |
1 |
Figure 1. All-cause mortality at 14 days among patients with NSTEMI or UA in the TIMI IIB trial, according to TIMI risk score (see Table 1).7
| Risk Factor | Score |
|---|---|
| Age >65 years |
2 |
| Age >75 years |
3 |
| History of angina |
1 |
| History of hypertension |
1 |
| History of diabetes |
1 |
| Systolic BP <100 mmHg |
3 |
| Heart rate >100 bpm |
2 |
| Killip class II-IV | 2 |
| Weight >67kg | 1 |
| Anterior MI or left bundle branch block | 1 |
| Delay to treatment >4 hours | 1 |
Figure 2. All-cause mortality at 30 days in patients with STEMI, according to TIMI risk score.3
References:
- Acute coronary syndromes (ACS). Available at: www.merck.com/mmpe/print/sec07/ch073/ch073c.html [accessed 4 August 2010].
- Bassand J-P, Hamm CW, Ardissino D, et al. Guidelines for the diagnosis and treatment of non-ST-segment elevation acute coronary syndromes. The Task Force for the Diagnosis and Treatment of Non-ST-Segment Elevation Acute Coronary Syndromes of the European Society of Cardiology. Eur Heart J 2007;28:1598-660.
- Kumar P, Clark M. Clinical medicine. 7th ed. Edinburgh: Saunders Elsevier, 2009.
- van de Werf F, Bax J, Betriu A, et al. Management of acute myocardial infarction in patients presenting with persistent ST-segment elevation. The Task Force on the management of ST-segment elevation acute myocardial infarction of the European Society of Cardiology. Eur Heart J 2008;29:2909-45.
- Goldberg RJ, Curry K, White K, et al. Six-month outcomes in a multinational registry of patients hospitalized with an acute coronary syndrome (The Global Registry of Acute Coronary Events [GRACE]). Am J Cardiol 2004;93:288-93.
- Lee KL, Woodlief LH, Topol EJ, et al. Predictors of 30-day mortality in the era of reperfusion for acute myocardial infarction: results from an international trial of 41,021 patients. GUSTO-I investigators. Circulation 1995;91:1659-68.
- Antman EM, Cohen M, Bernink PJLM, et al. The TIMI risk score for unstable angina/non-ST elevation MI: a method for prognostication and therapeutic decision making. JAMA 2000;284:835-42.