Should You Use Killip Classification in NSTEMI?
Yes, you should use the Killip classification in NSTEMI patients as it is a validated component of major risk stratification tools and independently predicts both in-hospital and long-term mortality.
Role in Validated Risk Scores
The Killip classification is explicitly incorporated into the GRACE risk model, which is the preferred comprehensive risk stratification tool for NSTEMI patients 1. In the GRACE nomogram:
- Killip Class I = 0 points
- Killip Class II = 20 points
- Killip Class III = 39 points
- Killip Class IV = 59 points 1
The 2017 AHA/ACC Performance Measures specifically recommend objective risk stratification with validated risk scores (GRACE >140 or TIMI >4) to guide timing of invasive strategy in NSTEMI, with high-risk patients benefiting from early invasive approach within 24 hours 1. Since Killip classification is a core component of GRACE scoring, its use is implicitly endorsed by these guidelines 1.
Independent Prognostic Value in NSTEMI
Beyond its role in composite scores, Killip classification has independent predictive value specifically in NSTEMI patients:
- A Korean registry of 2,148 NSTEMI patients demonstrated that Killip class (II: 1 point, >II: 2 points) was an independent predictor of one-year mortality when combined with TIMI risk index and creatinine 2
- Brazilian validation studies confirmed Killip classification as a significant, sustained, and independent predictor of long-term mortality in NSTEMI patients (Wald χ² 16.5, p=0.001), with a similar prognostic pattern to STEMI 3
Practical Application Algorithm
At presentation, assess Killip class clinically:
- Killip I (no heart failure): No rales, no S3 gallop
- Killip II (mild-moderate HF): Rales in lower half of lung fields or S3 gallop
- Killip III (severe HF): Rales extending >50% up lung fields (pulmonary edema)
- Killip IV (cardiogenic shock): Hypotension with signs of hypoperfusion 1
Then integrate into GRACE score along with age, heart rate, systolic blood pressure, creatinine, cardiac arrest status, ST-segment deviation, and elevated cardiac enzymes to calculate in-hospital mortality risk 1.
Use the combined risk assessment to determine invasive strategy timing: GRACE >140 warrants early invasive approach (<24 hours), while intermediate risk (GRACE 109-140) allows delayed invasive strategy (24-72 hours) 1.
Common Pitfalls to Avoid
Do not rely on Killip classification alone for NSTEMI risk stratification—it must be combined with other validated tools like GRACE or TIMI scores, as the 2014 AHA/ACC guidelines emphasize multivariable risk assessment 1. The GRACE model (C-statistic 0.83) provides superior discrimination compared to single variables 1.
Recognize that Killip II-IV in NSTEMI carries similar prognostic weight as in STEMI, despite the absence of ST-elevation 3. Studies show Killip class >I significantly increases both in-hospital and long-term mortality in NSTEMI patients 2, 3.
Document Killip class at admission, as it influences not only immediate management decisions but also predicts outcomes at mean follow-up of 5 years post-MI 3. The classification remains valid across the modern era of reperfusion and antithrombotic therapies 3.
Evidence Strength
The recommendation to use Killip classification in NSTEMI is supported by Class I Level A evidence for risk stratification in the 2014 AHA/ACC NSTE-ACS guidelines, which explicitly include Killip class in the GRACE risk model examples 1. Multiple validation studies in NSTEMI-specific populations confirm its independent prognostic value 2, 3.