What is Complex Angioplasty?
Complex angioplasty refers to percutaneous coronary intervention (PCI) performed on anatomically challenging lesions or in high-risk clinical scenarios that extend beyond the original simple, discrete, proximal, noncalcified stenoses in single vessels that characterized early angioplasty practice.
Evolution from Simple to Complex Procedures
When Andreas Gruentzig introduced coronary angioplasty in 1977, the technique was initially applied only to patients with discrete, proximal, noncalcified subtotal occlusive lesions in a single coronary artery 1. However, as equipment improved and operator experience grew, the definition of what could be treated expanded dramatically 1.
Anatomic Features Defining Complex Angioplasty
Complex angioplasty now encompasses several challenging anatomic scenarios:
Lesion Characteristics
- Multivessel disease requiring intervention in multiple coronary arteries 1
- Multiple subtotal stenoses in the same vessel 1
- Chronic total occlusions, particularly those of recent vintage 1
- Distal and bifurcation stenoses that involve vessel branch points 1
- Long lesions and geometrically complex stenoses classified as ACC/AHA lesion types B and C 1
- Stenoses at the origin of vessels or branch vessel stenoses 1
- Calcified lesions and tortuous vessels 2
Graft-Related Lesions
- Saphenous vein bypass graft stenoses, particularly in the proximal and middle regions (which have higher restenosis rates of approximately 50%) 1
- Internal mammary artery graft stenoses 1
- Degenerated saphenous vein graft lesions 2
Thrombotic Lesions
- Recent total thrombotic occlusions in acute myocardial infarction 1
- Thrombotic lesions requiring intervention 1, 2
Clinical Scenarios Defining Complexity
Beyond anatomic factors, complex angioplasty includes high-risk clinical situations:
- Unstable angina 1
- Acute myocardial infarction requiring emergent intervention 1
- Congestive heart failure 1
- Cardiogenic shock 1
- Elderly and very elderly patients turned down for surgical revascularization 2
- Patients with significant comorbidities including diabetes mellitus 1, 2
Key Distinction: Incomplete Revascularization
A critical feature distinguishing complex from simple angioplasty is the frequent inability to achieve complete revascularization. In the NHLBI Registry, when multivessel disease patients were analyzed for completeness of revascularization (defined as no residual lesions >50% narrowing), only one-third qualified 1. This inherent limitation occurs because:
- Chronic total occlusions may be inaccessible 1
- Mild lesions (50-60% stenosis) are typically not treated 1
- Morphological factors preclude successful dilation of all lesions 1
- Diffuse atherosclerotic disease without discrete segments cannot be addressed 3
Common Pitfalls and Caveats
The shift to complex cases has occurred despite limited robust evidence. The majority of early registry data came from patients with single-vessel disease (75% in the first NHLBI Registry) 1. As noted in recent literature, we are confronted with an increasing patient population that is "understudied and potentially underserved" 2.
Restenosis rates are higher in complex lesions. Factors predisposing to restenosis in complex angioplasty include proximal left anterior descending location, chronic total occlusions, branch vessel stenoses, long lesions, presence of thrombus, and saphenous vein graft involvement 1.
Success rates vary by complexity. While overall success rates improved from 61% to 78% between the first and second NHLBI registries, patients with multivessel disease had lower success rates (73%) compared to single-vessel disease 1.
Modern Context
By the 1990s and beyond, the case mix shifted dramatically—from only 25% of patients having multivessel disease in the initial NHLBI Registry to 53% in the subsequent registry 1. This trend has continued, with complex PCI now representing a significant proportion of interventional cardiology practice, driven by aging populations and patients with multiple comorbidities who are not surgical candidates 2.