Why does a stent not prevent cardiac deaths?

Why Coronary Stents Do Not Prevent Cardiac Deaths

Coronary stents primarily improve symptoms rather than prevent cardiac deaths in stable coronary artery disease, as they address localized blockages but do not modify the underlying systemic disease process that leads to most cardiac mortality. 1

Mechanism of Stent Limitations

• Stents are designed to mechanically support narrowed coronary arteries by providing a scaffold that maintains vessel patency, but they only treat discrete lesions rather than the widespread atherosclerotic process 2
• While stents effectively relieve angina symptoms by improving blood flow to ischemic myocardium, they don't address the progressive nature of atherosclerosis throughout the coronary vasculature 1
• Stent placement treats only the "culprit lesion" but doesn't prevent new plaque ruptures at other sites in the coronary tree, which are often the cause of fatal cardiac events 3

Evidence from Clinical Studies

• In stable coronary artery disease, stents have not demonstrated significant mortality benefits compared to optimal medical therapy alone 4
• A systematic review of 97 trials with 75,754 patients showed that coronary stents were not associated with a lower risk of death compared to optimal medical therapy 4
• Both bare-metal stents and drug-eluting stents show similar mortality rates (3.2% vs 4.1%, p=0.37) with no difference in cardiac mortality (1.4% vs 1.3%, p=0.55) at 2.6 years follow-up 5

Causes of Death After Stenting

• In real-world settings, cardiac and non-cardiac causes contribute almost equally to mortality after stent placement 6
• The predominant cardiac causes of death after stenting include:
  • Stent thrombosis (1.1% of total mortality) 6
  • Heart failure progression (1.4% of total mortality) 6
  • Myocardial infarction at non-stented sites 6
• Non-cardiac deaths (cancer, infection, respiratory failure, etc.) account for approximately half of all deaths after stent placement 5, 6

Stent Thrombosis Risk

• Stent thrombosis, while rare, carries a high mortality risk and can occur despite stent placement 3
• Early stent thrombosis (within first 30 days) is associated with a 30-fold greater risk of mortality 3
• Premature discontinuation of dual antiplatelet therapy significantly increases the risk of stent thrombosis and subsequent mortality 3
• Bare-metal stent thrombosis is most common in the first 2-4 weeks after placement but becomes exceedingly rare (<0.1%) after endothelialization occurs 3

Contrast with Bypass Surgery

• Unlike stents, coronary artery bypass grafting (CABG) has demonstrated mortality benefits compared to optimal medical therapy (OR = 0.84; 95% CI: 0.71-0.97) 4
• CABG provides more complete revascularization and protection against progression of disease in proximal vessels 1
• For multivessel disease, CABG shows a mortality benefit compared to PCI at 5-8 years, as well as less angina and less need for repeat revascularization 1

Clinical Implications

• Stents should be considered primarily for symptom relief in stable coronary artery disease when medical therapy is inadequate 1
• In acute coronary syndromes (particularly STEMI), stents may offer mortality benefits compared to fibrinolytic therapy 1
• For high-risk anatomical scenarios (left main disease, multivessel disease, especially in diabetics), CABG may offer greater mortality benefits than stenting 1
• Dual antiplatelet therapy adherence is crucial after stenting to prevent thrombosis, but even with optimal therapy, stents don't significantly reduce long-term cardiac mortality in stable disease 3