Relative Risk Reduction in Coronary Catheterization
Coronary catheterization itself does not provide a relative risk reduction (RRR) - it is a diagnostic procedure, not a therapeutic intervention. The RRR comes from the treatments guided by catheterization findings, specifically revascularization procedures like PCI or CABG.
Understanding the Distinction
Coronary catheterization is purely diagnostic - it visualizes coronary anatomy to identify obstructive lesions but does not directly reduce cardiovascular risk 1. The procedure carries inherent risks including:
- Mortality: 0.08-0.14% for diagnostic catheterization alone 1
- Myocardial infarction: Rare with diagnostic catheterization 1
- Stroke, bleeding, vascular complications: Occur infrequently 1
RRR from Catheterization-Guided Revascularization
When catheterization identifies significant coronary disease and leads to early revascularization, the mortality benefit is substantial:
Early Revascularization Benefits
- STEMI patients: Early revascularization reduces adjusted mortality risk by 27% (adjusted hazard ratio 0.73,95% CI 0.58-0.90) 2
- NSTEMI patients: Early revascularization reduces adjusted mortality risk by 24% (adjusted hazard ratio 0.76,95% CI 0.65-0.89) 2
- Coronary revascularization procedures: Reduce risk by approximately 24-34% per 1-mmol/L LDL-C reduction when combined with statin therapy 1
Acute Coronary Syndrome Context
In patients with acute coronary syndromes undergoing catheterization followed by intervention, the benefit is time-dependent. Weekend presentation delays catheterization by a median of 23 hours (46.3 vs 23.4 hours), but this delay was not associated with increased mortality when contemporary medical therapy was used 1. However, very early intervention (within hours) may be superior to delayed intervention in high-risk patients 1.
Critical Clinical Implications
The value of catheterization lies entirely in its ability to guide appropriate revascularization decisions, not in the procedure itself. Three-quarters of patients undergoing routine catheterization can be identified by noninvasive variables as being at such low risk that invasive intervention is unlikely to improve prognosis 3.
Risk Stratification Matters
- Low-risk patients: Annual cardiac mortality rate of 1% - catheterization unlikely to improve outcomes 3
- Moderate-risk patients: Annual mortality rate of 7% - may benefit from catheterization-guided intervention 3
- High-risk patients: Annual mortality rate of 12% - most likely to benefit from early catheterization and revascularization 3
Common Pitfalls to Avoid
Do not confuse diagnostic catheterization with therapeutic intervention. The procedure itself provides no RRR - only the subsequent revascularization based on catheterization findings reduces cardiovascular events 1, 2. Performing catheterization on low-risk patients identified by noninvasive testing exposes them to procedural risk without meaningful prognostic benefit 3.
Avoid catheterization in patients with borderline stenoses (<60%) unless objective evidence of myocardial ischemia is present, as dilation carries risk of more severe restenosis 1.