The question comes to mind because there are some studies that shows that even if the heart does not improve ejection fraction postoperatively in patients with severe LV dysfunction, there survival and symptomatic improvement is just like those patients who have increase in ejection fraction. So revascularization helps in both categories of patients. If it helps anyway, then why do we go for viability scan? Why not just revascularize every patient and hope that some patches of hibernating myocardium may get benefit?
A valid point but two caveats:
1. If patient is symptomatic with angina it is a proof positive sign of ischaemia nd there is no merit in doing a Thallium study.
2. If however patient is asymptomatic or symptomatic with failure then sure enough we need to do a viability scan espl if ventricular myocardium is thinned out or there is severe PAH -PA Systolic >70 mm of Hg, as not only benefits to be derived are going to be subjudice but operative risks high.
If a patient has large amount of myocardium in jeopardy, can lie flat, can Walk a flight of stairs without symptoms, does not have pulmonary venous hypertension on Chest X Ray, then your premise is valid nd irrespective of Thallium findings, I would recommend surgery , but all this I am talking unfortunately has Level of Evidence C.
We do viability test in three conditions:
Improving EF after revascularization is not the only factor that help patient to survive.50% of mortality in patients with heart failure is due to sudden death and arrhythmia and not heart failure, and most of these arrhythmia come from ischemia.With improving ischemia even if we would not have improved EF these fatal events will be prevented.
Hi Imran,
I love pathophysiology but this is a clinical question. I would suggest you to go over the latest ESC guidelines on myocardial revascularisation. What is new in these guidelines is that they stress the importance of imaging techniques for risk stratification. You have to document function at rest and during exercise and you have to quantitate the area that becomes ischaemic. In the presence of preserved EF you will only consider an intervention if your ischaemia was shown to be present > 10% of LV mass. So for that you need RN, stress echo or more sophisticated and less practical methods.
The guidelines are enclosed.
Best regards,
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