Читать книгу Practical Cardiovascular Medicine - Elias B. Hanna - Страница 44

If the coronary angiogram shows normal coronaries or minimal disease, the patient is at a very low risk of ischemic events in the ensuing 5 years and the coronary angiogram does not need to be repeated unless there is objective evidence of MI.

The coronary angiogram may show single- or multivessel moderate disease (40–70%), or severe disease (> 70%) in a small branch for which PCI is not technically possible or beneficial. The true functional significance of intermediate stenoses (40–70%) is worth assessing using fractional flow reserve (FFR) (during which the drop in flow across a stenosis is assessed using a pressure wire and maximal hyperemia). While FFR is mainly studied in stable CAD, the FAMOUS-NSTEMI trial and a large prospective European registry have shown that, in the setting of MI, PCI may be safely deferred for lesions with insignificant FFR >0.80.^128,129

Table 1.5 Prognosis of NSTEMI.

	30 days	1 year	5 years
Death	3%	4–5%	10% (1% per year past the first year)
Death or MI	5% (early invasive) 10–14% (early conservative)	10% (early invasive) 15% (early conservative)	20% (2% per year past the first year)
Death, MI, recurrent ACS, or revascularization		15–20%	30% (3–5% per year past the first year)

The most important numbers to remember are 5% death and 10% death/MI at 1 year despite PCI and optimal therapy. The rates herein provided are derived from clinical trial data. Real-world patients tend to be older with more comorbidities and more extensive disease, and thus have higher event rates.

Intracoronary imaging with OCT or IVUS is also useful to assess moderate NSTEMI lesions. In fact, in NSTEMI, the question is not only whether the lesion is functionally significant but whether the lesion is anatomically significant and likely to acutely progress (e.g., plaque rupture, thrombus). The goal of therapy in NSTEMI is to reduce the high risk of recurrent infarction rather than just improve angina; hence, the assessment of anatomy is more valuable in NSTEMI than in stable CAD. A thrombotic lesion that is not functionally significant at one point in time may still progress within days or weeks. In addition, the true lumen of a ruptured or ulcerated plaque may be much narrower than its angiographic appearance (contrast seeps through the planes of the ruptured plaque beyond the true lumen, giving the impression of a large lumen that is, nonetheless, hazy).

Figure 1.9 The concentric and eccentric lesions with smooth borders are predominantly seen in stable CAD, while the lesions with irregular or overhanging borders are predominantly seen in ACS. Haziness may be due to an unstable fissured plaque, with contrast faintly seeping through the fissures of the plaque beyond the true lumen; it may also be due to concentric calcium surrounding the lumen and does not necessarily imply instability.

Table 1.6 Angiographic findings in NSTE-ACS and rates of revascularization.^59-61

Angiographic findings	Revascularization
Insignificant disease or normal coronaries ~10% 1-vessel CAD ~30% 2-vessel CAD ~30% 3-vessel CAD ~30% Left main disease ~10%	PCI in ~60–70% CABG in ~10–15% No revascularization in ~30%

Even in NSTEMI patients whose symptoms and electrocardiographic ischemia are quickly stabilized with medical therapy, an untreated culprit stenosis of > 50% has a 25% chance of progression within 8 months, mostly to a total occlusion, more so when the lesion has a complex appearance; note that this study was performed before the era of widespread statin and ADP receptor antagonist use.¹³⁰

Conversely, the progression is much slower in stable CAD stenoses >50% (<10% progression rate per lesion at 1.3 years with <2-3% ACS) (COURAGE trial).¹³¹

Non-culprit stenoses have a slow progression in both MI or stable CAD: the summation risk of angina progression from all lesions is ~6% at 1 year and ~10% at 3 years of follow-up, mostly arising from lesions <50%, more so in the presence of complex angiographic or IVUS features, with only 1% death/MI from all these lesions at 3 years (PROSPECT trial).^126,130