CABG vs PCI (STENTING) DIFFERENCE IN MEHCANISM

In Bypass Graft Surgery there is no metallic or foreign body is used inside the blocked artery. In CABG natural available grafts (artery or vein) is used to place it on healthy part of the blocked artery and does not disturb the disease in the artery.  Bypass of a coronary artery improves blood flow

to the jeopardized heart muscle supplied by the diseased

artery and also protect the distal heart muscles beds from future ischemic insult (heart attack) caused by proximal disease progression, plaque  progression or rupture .

PCI (STENTING) procedure involves opening of the coronary artery by directly relieving a localized  obstruction and placing a metallic stent coated with drugs to maintain the patency of the arterial lumen. This increases the arterial lumen in the stented area but have no effect on preventing disease progression, plaque progression or rupture in other diseased segments within the artery.

Acute Coronary Syndrome (ACS) is group of symptoms associated with acute coronary artery ischemia. ACS is defined as STEMI (ST- elevation myocardial infarct) when ECG findings with ST segment elevation is evident. It occurs due to the complete and prolonged occlusion of an epicardial coronary artery.

ACS in which there is no ECG findings of ST  segment elevation is defined as NSTEMI (Non-ST elevation MI). It is due to  severe coronary artery narrowing, transient occlusion, or microembolization of thrombus and/or atheromatous plaque material.

 Stable ischemic heart disease (SIHD)  is the condition in which there is mismatch between demand and supply of the blood to the heart muscle. It is due to the chronic occlusion of the heart arteries but there is no sign and symptoms of the acute heart muscle damage as in STEMI.

Left main artery divides in two ( LAD and LCX) or sometimes three (LAD,LCX and RI). The disease involving in the main segment of this artery is left main disease.

Coronary artery disease involving only one vessel. This could involve only LAD or other artery.

Disease involving more than one vessels. When the disease involve all the three arteries , its is known as TVD( Triple- Vessel Disease) .

 At each milestone in percutaneous technology, PCI has been tested against the “gold standard” of CABG with respect to effects on mortality and quality of life. Randomized trials have shown superiority of CABG over PCI in patients with higher disease burden and lesion complexity1 and in the presence of diabetes.2 

 However, for the relatively healthy patients with multivessel coronary disease represented in this trial, we should conclude that CABG is the preferred approach, with the understanding that there are increased short-term risks inherent with CABG. A putative advantage of CABG in this context is that the use of surgical grafts bypasses not only the flow-limiting lesion but also a substantial length of coronary vessel, and subsequent atherothrombotic events along that length are rendered less impactful. 

 January 13, 2022
N Engl J Med 2022; 386:185-187
DOI: 10.1056/NEJMe2117325 

 1.Serruys PW, Morice MC, Kappetein AP, et al. Percutaneous coronary intervention versus coronary-artery bypass grafting for severe coronary artery disease. N Engl J Med 2009;360:961-972. 

 2.Farkouh ME, Domanski M, Sleeper LA, et al. Strategies for multivessel revascularization in patients with diabetes. N Engl J Med 2012;367:2375-2384. 

 In patients with acute heart attack STEMI and symptoms

for <12 hours, PCI (Stenting) should be performed

to improve survival. 

But if the patient has cardiogenic shock or hemodynamic instability, PCI or CABG(when PCI(stenting) is not feasible) is indicated to improve survival, irrespective of the time delay

from MI onset.

The patients who have mechanical complications (like VSR, Severe MR due to papillary muscle infarction or rupture, or free wall rupture), CABG is recommended.

In asymptomatic stable patients who have a totally occluded infarct artery >24 hours after symptom onset and are without evidence of severe ischemia, PCI(stenting) should not be performed.

In patients with STEMI, emergency CABG should

not be performed after failed primary PCI:

 In the absence of ischemia or a large area of

myocardium at risk, or

 If surgical revascularization is not feasible because

of a no-reflow state or poor distal targets.

 In selected hemodynamically stable patients with acute heart attack STEMI and multivessel disease, after

successful primary PCI, staged PCI of a significant

non-infarct artery stenosis is recommended

to reduce further risk of death or heart attack.

 In some patients with STEMI with complex multivessel non-culprit  artery disease, after successful primary PCI, elective CABG is reasonable to reduce the risk of heart attack or other heart problem related to ischemia.

In some stable patients with STEMI and low-complexity multivessel disease, PCI of a non-culprit artery stenosis

may be considered at the time of primary PCI to reduce cardiac event rates.

In patients with acute heart attack STEMI complicated by cardiogenic shock, routine PCI of a non-culprit vessel  at the time of primary PCI should not be performed because of the higher risk of death or kidney failure.

The patients with SIHD and multivessel CAD (TVD) with severe LV dysfunction (LVEF < 35%) fit for surgery,  for them CABG is recommended to improve survival.

In some patients with SIHD and multivessel

CAD (or TVD) with mild to moderate LV dysfunction (LVEF 35% to 50%) fit for surgery CABG (with internal mammary arterial graft to the LAD(LIMA-LAD)) is reasonable to improve survival.

There is no study till date which proves survival benefits of PCI (Stenting) in theses cases. Survival benefits are uncertain with PCI (Stenting)

In patients with SIHD who have significant left main disease, CABG is recommended to improve survival. (Class I recommendation).

In some patients with SIHD (low complex disease) and significant left main disease for whom PCI(Stenting) can provide equivalent revascularization to that possible with CABG,PCI(Stenting) is reasonable to improve survival.(Class 2a Recommendation).

The Syntax Score should be used to define the complexity of the multiple vessel disease.

In patients with SIHD, normal LV significant stenosis in 3 major coronary arteries (with or without proximal LAD), and

anatomy suitable for CABG, CABG may be reasonable to improve survival.

In patients with SIHD, normal LV significant stenosis in 3 major coronary arteries (with or without proximal LAD), and

anatomy suitable for PCI, the usefulness of

PCI to improve survival is uncertain.

 In patients with SIHD, normal LVEF, and significant stenosis in the proximal LAD, the usefulness of coronary

revascularization (CABG or PCI) to improve survival is uncertain.