The Evidence for Catheterization and Stenting

Introduction

For decades, the logic seemed self-evident: blockages cause heart attacks, so opening blockages should prevent them. Catheterization identifies blockages, stenting opens them, and patients should live longer as a result. This intuitive reasoning drove exponential growth in coronary intervention, with millions of stents implanted annually worldwide.

Then came the trials that challenged this paradigm. COURAGE in 2007 showed no mortality benefit from stenting stable coronary disease. ORBITA in 2018 demonstrated that stenting might not even improve symptoms better than a sham procedure. ISCHEMIA in 2020 confirmed that even patients with documented ischemia did not live longer with routine catheterization and intervention. These results shook interventional cardiology and forced reconsideration of when invasive approaches truly help.

This article reviews the evidence for catheterization-guided intervention, distinguishing scenarios where benefit is clear from those where it is questionable or absent. Understanding this evidence is essential for patients facing decisions about whether to proceed with catheterization and potential stenting. Related articles address how to interpret findings and how to navigate decisions when faced with results that could support multiple approaches.

What clinical outcomes does diagnostic catheterization improve compared to non-invasive testing alone?

Diagnostic catheterization provides information that non-invasive tests cannot match in anatomical detail. However, better information does not automatically translate to better outcomes. The value of catheterization depends on whether the additional information changes management in ways that improve patient outcomes—not simply whether it reveals disease.

For patients with acute coronary syndromes, early catheterization enables identification and treatment of culprit lesions, improving survival. The benefit of urgent catheterization in STEMI is overwhelming and not seriously disputed. In high-risk NSTEMI, early invasive strategies also show outcome benefits. These represent settings where catheterization reveals actionable anatomy requiring time-sensitive intervention.

For stable patients, the calculus differs. The ISCHEMIA trial randomized over 5,000 patients with stable coronary disease and documented moderate-to-severe ischemia to invasive versus conservative management (Reynolds et al., 2021). After a median follow-up of 3.2 years, routine catheterization and revascularization did not reduce death or myocardial infarction compared to medical therapy. The additional information catheterization provided did not translate to better survival.

For stable coronary artery disease, does stenting reduce heart attacks or extend life compared to medications alone?

The answer, supported by multiple large trials, is generally no. For patients with stable coronary disease—chest pain that is predictable, manageable, and not rapidly progressing—stenting does not reduce heart attack rates or extend life compared to optimal medical therapy alone.

The COURAGE trial enrolled 2,287 patients with stable coronary disease and objective evidence of ischemia (Boden et al., 2007). Half received PCI plus optimal medical therapy; half received optimal medical therapy alone. After 4.6 years of follow-up, death and myocardial infarction rates were identical between groups. The trial was initially criticized for enrolling patients with mild disease, but subsequent analyses confirmed the findings held across disease severity strata.

The ISCHEMIA trial addressed COURAGE’s limitations by enrolling only patients with moderate-to-severe ischemia on stress testing—patients traditionally thought most likely to benefit from revascularization. Again, routine invasive management provided no survival advantage. The invasive group experienced more procedural myocardial infarctions, while the conservative group had more spontaneous infarctions; total event rates were equivalent.

What did the COURAGE, ORBITA, and ISCHEMIA trials find about stenting for stable disease?

COURAGE established that stable coronary disease patients with documented ischemia do not live longer with PCI than with medical therapy alone. The finding challenged prevailing practice and generated controversy, but the data were clear: stenting did not reduce death or myocardial infarction rates over nearly five years of follow-up.

ORBITA took a methodologically unprecedented approach by randomizing stable angina patients to either PCI or a sham procedure after diagnostic catheterization (Al-Lamee et al., 2018). All patients underwent catheterization, received the same sedation, heard the same sounds, and recovered identically. Only the randomization determined whether their blockage was actually stented. The remarkable finding: exercise time improved similarly in both groups. Stenting was no better than placebo for improving functional capacity.

ISCHEMIA enrolled a larger, sicker population than COURAGE and confirmed the earlier findings. Even patients with severe ischemia—the traditional argument for aggressive intervention—showed no mortality benefit from routine catheterization and revascularization. The trial did show some symptom improvement with invasive management, but this benefit was modest and potentially explained by placebo effects that ORBITA had exposed.

For which patients does catheterization-guided intervention clearly improve survival?

Acute coronary syndromes represent the clearest indication. During STEMI (ST-elevation myocardial infarction), immediate catheterization and revascularization of the culprit lesion reduces mortality substantially compared to medical management alone. The benefit is time-dependent—every minute of delay increases heart muscle loss and worsens outcomes. Emergency catheterization for STEMI is not controversial.

High-risk NSTEMI patients also benefit from early invasive strategies. Trials comparing early versus delayed catheterization in acute coronary syndromes show better outcomes with prompt invasive evaluation. The FRISC-II, TACTICS-TIMI 18, and other trials established that higher-risk patients with positive biomarkers, dynamic ECG changes, or recurrent ischemia benefit from catheterization within 24-72 hours.

Beyond acute presentations, survival benefit is more limited. Left main disease and multivessel disease with reduced left ventricular function show survival advantage with revascularization in some trials, though whether this benefit comes from PCI or bypass surgery varies by anatomy. The SYNTAX trial and subsequent analyses suggest complex multivessel disease benefits more from surgical revascularization (Ong et al., 2006).

What is the evidence for catheterization and intervention in acute heart attacks?

Primary PCI for STEMI is among the most evidence-based interventions in cardiovascular medicine. Multiple trials demonstrated substantial mortality reduction when culprit arteries are opened within hours of acute occlusion. The survival benefit comes from salvaging myocardium that would otherwise die—tissue that will infarcted if blood flow is not restored.

The time element is critical. “Door-to-balloon time”—the interval from hospital arrival to restoring blood flow—directly correlates with outcomes. Systems of care have been redesigned around minimizing this interval. Catheterization labs maintain 24/7 readiness for STEMI patients. The evidence supporting emergent PCI for STEMI is overwhelming and well-accepted.

NSTEMI represents a more nuanced situation. Unlike STEMI, where complete arterial occlusion is obvious on ECG, NSTEMI involves partial occlusion or microvascular injury with various risk levels. Multiple trials show benefit from early invasive strategies in higher-risk patients, but the optimal timing remains debated. Very early catheterization (within 2 hours) does not clearly improve outcomes over early catheterization (within 24-72 hours) except in the highest-risk subset.

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How large is the benefit of primary PCI for heart attacks in absolute terms?

For STEMI, the absolute mortality reduction from primary PCI compared to fibrinolytic therapy (clot-dissolving drugs) is approximately 2-3% at 30 days in trials, translating to roughly 20-30 lives saved per 1,000 patients treated. When primary PCI is compared to no reperfusion therapy, the benefit is substantially larger.

The mortality reduction translates to a number needed to treat (NNT) of approximately 33-50 for STEMI—meaning 33-50 patients need primary PCI rather than fibrinolysis to save one additional life at 30 days. This represents a substantial treatment effect by medical standards, justifying the infrastructure required to provide 24/7 primary PCI capability.

Beyond mortality, primary PCI reduces reinfarction rates and recurrent ischemia compared to fibrinolysis. It also enables definitive characterization of coronary anatomy, identifying patients who need urgent bypass surgery and those who may require additional intervention for non-culprit lesions. The evidence supporting primary PCI for STEMI is among the strongest in cardiovascular medicine.

What is the number needed to treat for stenting in different clinical scenarios?

For stable coronary disease without recent acute coronary syndrome, the number needed to treat for mortality reduction approaches infinity—because the trials show no mortality benefit. You could stent thousands of stable patients and not save a single additional life compared to medical therapy alone based on COURAGE and ISCHEMIA data.

For symptom relief in stable angina, the NNT varies by outcome definition. The ORBITA trial suggested stenting provided no symptom benefit beyond placebo. Other trials show modest improvements in angina frequency, but the effect sizes are small. If roughly 10-15% more patients achieve angina freedom with PCI versus medical therapy, the NNT for this outcome would be 7-10.

For acute coronary syndromes, NNT depends on baseline risk. The FAME 2 trial showed FFR-guided PCI in patients with stable CAD and functionally significant lesions reduced urgent revascularization with an NNT of approximately 20 over two years (De Bruyne et al., 2012). This represents a composite outcome heavily weighted toward repeat procedures rather than mortality or infarction.

Does catheterization-based intervention reduce symptoms better than medical therapy?

The evidence for symptom reduction is more complex than initially assumed. Traditional teaching held that opening blockages would immediately relieve angina by restoring blood flow to ischemic muscle. Trials do show some symptom benefit with intervention, but the magnitude is modest and may be partly explained by placebo effects.

The ORBITA trial’s sham-controlled design was specifically intended to test whether symptom improvement with PCI reflected true physiological benefit or placebo effect (Al-Lamee et al., 2018). The finding that exercise capacity improved equally with PCI and sham procedure suggests substantial placebo contribution. Patients expected to feel better after “having their blockage fixed,” and they did—regardless of whether it was actually fixed.

ISCHEMIA showed greater symptom improvement with invasive management, but the magnitude was modest. At one year, about 50% of invasive-group patients were angina-free compared to 44% in the conservative group—an absolute difference of 6%. Some of this difference likely reflects placebo effects given ORBITA’s findings. For patients whose primary goal is symptom relief, the expected benefit from intervention is smaller than commonly assumed.

How durable are the benefits of stenting—do they persist over years?

Symptom benefits from stenting tend to diminish over time. Initial relief from opening a blockage may fade as disease progresses elsewhere, restenosis develops, or medical therapy progressively improves symptoms in patients initially managed conservatively. Long-term follow-up of trials shows convergence between intervention and medical therapy groups.

Procedural complications from stenting persist indefinitely. A stent requires lifelong consideration—dual antiplatelet therapy for at least a year, potential complications including late stent thrombosis and restenosis, and imaging challenges when evaluating stented segments. The decision to stent is not reversible; a patient cannot later choose to “un-stent” if preferences change.

Long-term follow-up of COURAGE showed sustained equivalence between PCI and medical therapy groups through 15 years. The absence of mortality benefit was not just a short-term phenomenon—it persisted across the long term. This suggests that the trials captured the relevant outcomes and did not miss late-emerging benefits from intervention.

What percentage of patients who undergo diagnostic catheterization proceed to intervention?

Practice patterns vary substantially across facilities, regions, and countries. In the United States, roughly 40-60% of diagnostic catheterizations lead to same-session intervention depending on the patient population and facility. This includes both ad hoc PCI (stenting during the diagnostic procedure) and staged procedures planned based on diagnostic findings.

Higher intervention rates do not necessarily reflect appropriate care. Geographic studies show dramatic variation in catheterization and PCI rates across regions that cannot be explained by differences in disease prevalence. Areas with more cardiologists and catheterization labs have higher intervention rates, suggesting supply-induced demand.

The ADAPT-DES registry examined outcomes across facilities with varying IVUS utilization and intervention patterns (Witzenbichler et al., 2013). The finding that IVUS-guided cases had better outcomes suggests that more careful lesion assessment—not simply more intervention—improves results. Proceeding to intervention should reflect careful evaluation, not automatic escalation.

What outcomes should I expect if catheterization shows no significant blockages?

A catheterization showing no significant obstruction provides reassurance regarding occlusive coronary disease but does not explain symptoms or eliminate risk. Patients with chest pain and normal coronary arteries may have microvascular disease, coronary spasm, or non-cardiac causes. The absence of obstructive disease does not mean the heart is entirely healthy.

Risk stratification improves with normal catheterization findings but remains above baseline. Non-obstructive disease visible on angiography—plaques that don’t meet threshold for significance—still carries prognostic implications. Studies show elevated cardiovascular event rates in patients with any angiographic disease compared to truly normal arteries.

For symptoms, further evaluation may be warranted. Microvascular function testing can identify impaired coronary flow reserve despite normal epicardial arteries. Spasm provocation testing can diagnose Prinzmetal angina. Non-cardiac evaluation may reveal esophageal disorders, musculoskeletal causes, or anxiety contributing to chest pain. Normal catheterization narrows the differential but does not complete the evaluation.

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How does the benefit of intervention vary by the number and location of blockages?

Single-vessel disease in a non-LAD artery represents the weakest indication for intervention in stable patients. COURAGE enrolled many such patients and showed no benefit. The amount of myocardium jeopardized is modest, medical therapy can often control symptoms, and intervention carries procedural risks without survival benefit.

Left anterior descending disease carries greater significance because of the large territory supplied. Proximal LAD stenosis in particular has been associated with higher risk in observational studies. However, ISCHEMIA subgroup analyses found that even patients with extensive disease involving proximal LAD did not clearly benefit from routine intervention compared to medical therapy.

Multivessel disease and left main disease have traditionally been considered indications for revascularization, often with bypass surgery rather than PCI. The SYNTAX trial and subsequent studies suggest surgical revascularization provides superior outcomes for complex multivessel disease, particularly when the SYNTAX score is high. However, these findings may reflect the superiority of CABG over PCI rather than the superiority of intervention over medical therapy.

What is the evidence for catheterization in patients with heart failure?

Heart failure with reduced ejection fraction and coronary artery disease presents a distinct clinical scenario. The STICH trial evaluated surgical revascularization versus medical therapy in patients with ischemic cardiomyopathy. Extended follow-up showed modest survival benefit with CABG—approximately 4% absolute mortality reduction at 10 years.

The REVIVED trial more recently examined PCI versus medical therapy for ischemic cardiomyopathy with viable myocardium and found no benefit from PCI. This suggests the STICH findings may reflect CABG-specific benefits (more complete revascularization, internal mammary artery grafts) rather than revascularization in general.

For patients with preserved ejection fraction and suspected coronary disease, the ISCHEMIA trial findings apply. Heart failure symptoms might be due to diastolic dysfunction, coronary disease, or both. Catheterization can clarify anatomy but does not guarantee therapeutic benefit from intervention.

How do outcomes differ between drug-eluting stents and bare-metal stents?

Drug-eluting stents (DES) release medications that inhibit neointimal proliferation—the tissue overgrowth that causes restenosis after bare-metal stent (BMS) placement. DES dramatically reduced restenosis rates compared to BMS, from approximately 20-30% to 5-10% depending on lesion characteristics.

The reduction in restenosis translates primarily to reduced repeat procedures rather than reduced mortality or myocardial infarction. Major trials comparing DES to BMS showed similar rates of death and MI with markedly lower target lesion revascularization in DES groups (Hong et al., 2015). Patients receiving DES need repeat procedures less often, representing a meaningful clinical benefit.

DES require longer durations of dual antiplatelet therapy (DAPT) compared to BMS because drug coatings delay endothelialization. This carries bleeding risk tradeoffs. Current generation DES with thinner struts and newer polymers may allow shorter DAPT durations, but standard practice remains 12 months of DAPT for most DES implantation scenarios.

What is the evidence comparing stenting to bypass surgery for multivessel disease?

The SYNTAX trial randomized patients with left main or three-vessel disease to PCI with drug-eluting stents versus CABG. Overall outcomes were similar at one year, but long-term follow-up favored CABG, particularly in patients with complex anatomy (high SYNTAX scores). The findings established that PCI and CABG are not interchangeable—complexity matters.

Subsequent trials have generally confirmed CABG superiority for complex multivessel disease. The BEST, NOBLE, and EXCEL trials each addressed aspects of this comparison. While results have been debated and some findings favored PCI for specific endpoints, the weight of evidence supports CABG for patients with extensive disease, particularly those with diabetes.

The mechanism of CABG’s advantage likely involves more complete revascularization and the unique biology of arterial grafts. The left internal mammary artery to LAD has exceptional long-term patency. Bypass grafts protect against disease progression in native vessels downstream of the anastomosis in ways that stents cannot.

Conclusion

The evidence regarding catheterization and stenting challenges intuitive assumptions about fixing blockages. For acute myocardial infarction, rapid revascularization clearly saves lives. For stable coronary disease, the benefit is limited to modest symptom improvement—and even this may be partly placebo effect.

These findings do not mean catheterization and stenting are useless. They mean patient selection matters enormously. The procedure that saves lives during a heart attack may provide no benefit—and pose only risk—for stable disease. Understanding this evidence positions patients to have more informed conversations about whether catheterization makes sense for their specific situation.

The next articles address evaluating evidence quality in catheterization research, controversies and debates within interventional cardiology, and how to navigate decisions when faced with catheterization recommendations.