Thank you for a very insightful and important question, the answer to which, interventional cardiologists such as myself have been battling with for the last few decades.
Essentially, we can break up your question into three parts:
- Significance of the location of the narrowing (proximal LAD)
- Significance of the narrowing of 80%
- Medical therapy or revascularisation (ie bypass or stent therapy) for the above with no symptoms
the answers to the queries above are,
- 1) the location of the narrowing in the proximal part (first third) of the LAD is significant as this artery supplies a large part of the heart muscle on the left side (the working side). Early studies from the 1980's looking at natural progression of proximal LAD disease noted worse prognosis in such lesions if untreated.
- 2) Any narrowing worse than 50% has been shown to affect flow as seen in perfusion scans (ie blood flow within heart muscle using radionuclides).
-3) well, there is a large body of evidence out there for both options (medical therapy only vs medical therapy combined with bypass or stent therapy).
As you can guess, there are very strong opinions on both sides. A large meta analysis from 2014 (i.e combining a few trials together - especially when individual trials gave conflicting results) – combined 95 trials in 93,553 patients, & concluded that bypass surgery and angioplasty using new-generation drug-coated stents reduces all cause mortality.
However, certain trials ie COURAGE and BARI-2D (two among many) supported optimal medical therapy alone, though there were many criticisms of the methodology and analyses.
I would suggest that IF there is objective evidence of ischemia (which is likely in a 80% lesion), then angioplasty or bypass is indicated for better prognosis.
Ischemia (poor blood flow due to the narrowing) is ideally assessed either by:
- FFR (i.e Fractional Flow Reserve, in the catheter laboratory, is accurate and it's easy to proceed to angioplasty if required at the same sitting - preferred option)
- or a Myocardial Perfusion Scan (non-invasive, carries some minimal risk and needs careful analysis)
Neither of the above is required if the treadmill is positive however. We also need to factor in risk factors and symptoms into the decision making.
As you can see, the discussion and decision to proceed are pretty complex, and better taken after an informed discussion in the clinic. I have added some links below for you to look at, though I am afraid they are somewhat technical.
Hope this is of some help, though I would urge you not to procrastinate.
Regards
Dr Nandakumar
