NurseSavvy Cheat SheetDisease
Stable Angina vs Unstable Angina
Pathophysiology & Risk Factors
Both present as chest pain, but the mechanism differs. Stable angina is a fixed atherosclerotic plaque that limits flow only when demand rises — predictable, exertion-triggered, and relieved by rest or nitroglycerin. Unstable angina is acute coronary syndrome: the plaque has ruptured or eroded and a partial thrombus critically narrows the vessel. Any change in a previously stable pattern reclassifies it as unstable and demands emergency evaluation.
Stable vs unstable angina
Stable anginaUnstable angina
TriggerExertion or stress (predictable)Rest or minimal exertion
Duration< 5 minutes> 15-20 minutes
Relief with rest / nitroglycerinRelieved by rest or SL NTGPartial or no relief with NTG
PatternConsistent, unchangedNew-onset or changing pattern
TroponinNegativeNegative (distinguishes from NSTEMI)
ManagementOutpatientInpatient emergency
Stable angina
- Trigger
- Exertion or stress (predictable)
- Duration
- < 5 minutes
- Relief with rest / nitroglycerin
- Relieved by rest or SL NTG
- Pattern
- Consistent, unchanged
- Troponin
- Negative
- Management
- Outpatient
Unstable angina
- Trigger
- Rest or minimal exertion
- Duration
- > 15-20 minutes
- Relief with rest / nitroglycerin
- Partial or no relief with NTG
- Pattern
- New-onset or changing pattern
- Troponin
- Negative (distinguishes from NSTEMI)
- Management
- Inpatient emergency
Signs & Symptoms
EarlyProgresses →
exertional chest pain
stable: triggered by exertion or stresspain relieved by rest
stable patternLate / Severe
decreased exertion threshold Hallmark
now triggered by minimal activity; signals unstablechest pain at rest Hallmark
unstable angina hallmarkprolonged chest pain
lasts > 15-20 minutespain more severe than usual
change from client's baseline patternOther findings
radiation to jaw
cardiac ischemia featureDiagnostics & Labs
cardiac troponin
negative in unstable angina; positive in NSTEMI/MI12-lead ECG
no ST elevation in unstable anginanegative biomarkers Hallmark
distinguishes unstable angina from NSTEMIInterventions & Priorities
recognize pattern change
shift from stable to unstable is the priority catchactivate rapid response
do not reassure and repositionadminister sublingual nitroglycerin
up to 3 doses, 5 minutes apartactivate EMS if unrelieved
after 3 NTG doses without reliefcontinuous cardiac monitoring
Treatments & Medications
sublingual nitroglycerin
up to 3 doses, 5 minutes apartPatient Teaching
stop activity at pain onset
rest is first-line for stable anginanitroglycerin 3-dose protocol
1 dose every 5 minutes, up to 3 dosescall EMS if unrelieved
after 3 doses without reliefreport any pattern change
new onset, more frequent, lower threshold, or rest painReport Nowescalate immediately
chest pain at rest Hallmark
departure from exertion-triggered stable patternnitroglycerin-resistant pain
no relief after 3 SL dosesnew-onset angina
qualifies as unstable even without prior cardiac historyescalating angina frequency
increasing frequency or lower thresholdpain lasting over 15 minutes
Clinical Pearl
Stable angina is a story the client has told before — same trigger, same relief. The moment the story changes, it's unstable, and you treat it like an emergency.