In one of our patients who had a recent STEMI , CAG revealed 70% LAD lesion with TIMI 1 flow .The distal run off was slow .He had moderate LV dysfunction with no major symptoms. The angiogram was done routinely .( Yes . . . routine CAG- the term I do not relish , while it is becoming a way of life for all learned cardiologists !)
I was discussing this case with my fellows and about medical management of CAD. I told them Aspirin will help prevent ACS, statins will stabilise the plaques , beta blocker would prevent cardiac events by blunting adrenergic surges and Nitrates is a powerful coronary vasodilator that will improve the coronary blood flow
A final year MD fellow threw a direct question at me .
Sir, do you mean Nitrates would increase the TIMI flow from 1 to 3 in the long term in this patient ?
I was taken-aback for a moment . . . and thanked my student for a valid question .
Nitroglycerine is a powerful coronary vasodilator we are taught for nearly half a century . Oral nitrates are used liberally in the chronic management of angina. It is a multi billion dollar market.
Has it been documented to improve coronary blood flow in the long term ?
Why then it is used long term ?
It is a clear case of inappropriate medical therapeutics .
* The confusion is partly due to our mix up the mechanism of relief of angina from coronary vasodilataion. Realistically , NTG should me known more as a powerful venodilator reducing the preload . It dramatically reduces the LV filing pressure and relieves sub-endocardial stress .This is the major determinant for angina relief .(Of course after-load reduction also helps)
Nitrates should be used only for relief of an episode of angina or just to prevent It .This may surprise you , Nitrates has no documented efficacy in the long term management of angina.