Heart tissue sustains damage within 30 minutes of being deprived of oxygen. A blood clot that completely blocks blood flow in a coronary artery and does not at least partially dissolve will cause heart attack.
Untreated chronic stable angina may progress to unstable angina, an acute coronary syndrome that requires immediate medical attention to prevent the development of
- severe arrhythmias (i.e., irregular heart rhythm),
- heart attack,
- or sudden cardiac deathdue to cardiac arrest with loss of consciousness within 1 hour of the onset of acute symptoms.
Possible complications of variant angina include the following:
- Atrioventricular block (i.e., absence of electrical conduction between the atrium and ventricle)
- Episodes of disabling pain
- Heart attack
- Severe arrhythmias
- Sudden cardiac death (sudden cardiac arrest [SCA])