Differential response of thrombolysis between left and right coronary system
- Thrombolysis is the specific treatment for acute myocardial infarction. ( Privileged few , get primary PCI))
- Failed thrombolysis occurs in significant number of patients ( 30-40%).
- Persistent ST elevation 120 minutes after thrombolysis is best indicator of failed thrombolysis.
- It has been a consistent observation failed thromolysis is more frequent in anterior or LAD myocardial infarction.
In a simple study we have documented patients with inferior MI rarely had persistent ST elevation and thrombolysis was successful in vast majority of patients ( Except in few patients associated lateral MI)
The mechanism of better thrombolysis in right coronary artery is simple.The success of thrombolysis , apart from early time window , is directly correlated with pressure head and the duration of contact between the thrombolytic agent and the thrombus. In right coronary circulation the blood flow is continuous , occurs both in systole and diastole that facilitates the maximum delivery of the thrombolytic agent . Further there is a favorable pressure gradient across RV myocardium as the transmural occluding pressure across RV is considerably less then LV myocardium.
This paper was presented in the “Annual cardiological society of India scientific sessions”
at Chennai, Tamil Nadu.India December 2000
Click to down load PPT full presentation
Dr.S.Venkatesan MD 
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dear sir,
i strongly would like to differ on this issue>
i am thrilled at the explanation given behind it.
i really like the physiological basis of systolic flow.
i agree that st segment resolution in inferior wall MI is better than the resolution in anterior wall MI.
but there is a paradox in this scenario.
in all cases of so called failed thromolysis(ECG diagnosed), when u do a coronary angiogram, the results are different.
i personally feel, the thrombus load in the RCA is higher
I have always found the incidence of ectasia also higher in RCA with a huge thrombus burden.
in LAD in most failed thrombolysis cases also, the thrombus burden is low, usually the failed thrombolysis is a no reflow phenomenon and that produces the clinical picture of failed thrombolysis.
i would wish to know whether there is any evidence of these findings in your patient subsets?
Hi , Dr Manokar
Thank you for your critical observation .
I do agree thrombus load could be little higher in RCA than LCA.It is well known RCA is a more uniform calibered conductance vessel .Tapering does not occur.
So thrombus formation may be more .
But the fact remains failed thrombolysis (or shall we call failed reperfusion ) in RCA is many fold less than LCA.In our institute , failed thrombolysis nearly 99 % occur in LCA. A huge statistical point !
What about yours ?
There should be some reason for it .
Presence of large thrombus load does not , in any way imply prompt reperfusion to distal RCA territory is impossible.
Flow limiting thrombus only matters. Further,
timing of these thrombus formation is also important.
Many times the thrombus load is a late event after a successeful initial thrombolysis.
There is no specific studies available on this issue.
It is difficult to recruit patients also. We know , Inferior MI outcome is many fold favorable and we have to decode the reason for it . Apart from lesser LV muscle mass supplied by RCA , One of the reasons could be this proposed hemodynamic advantage during both spontaneous or pharmacological thrombolysis.
Ofcourse ,we have look into this again in our Primary PCI cohort.
I wish you take on this work in your institute
Dr . Venkatesan
hmmm…
Dr . Venkatesan… are u specialist doctor…??
OMG.. how to makes an detail article like that….
nice share btw
Dear Dr. Venkasetan,
Could you please provide a reference to your claim that failed thrombolysis occurs 99% of the time in the LAD? This reference from France, for example, suggests otherwise. http://www.ncbi.nlm.nih.gov/pubmed/10816805
Regards,
Michel Accad, MD
Thank you for your comment.
I agree with you . I should not have used word almost always .I will correct that . But still LAD constitutes the bulk of failed lysis.
The point i am trying to convey is purely based on CCU data (Not CAG based which would be more ideal )
In our observation failed thrombolysis was defined by clinical criteria (To be precise mainly by ST segment regression )
in my experience it is very uncommon to see persistent ST elevation in inferior leads after thrombolysis.
( Again this may be attributable to the relatively reduced muscle mass of infero-posterior areas of heart.
Further , the relationship between successful thrombolysis and the resultant reperfusion is not linear.)
There was a time , when there was a strong argument against routine thrombolysis in RCA infarct
this if we look in retrospect has some meaning !
venkatesan
Thank you your honest response.
If I may, I would still question your assertions:
ST elevation MI is most frequently associated with an occlusive thrombus. Therefore the argument of coronary flow dynamics that you employ may not apply. If the thrombus is occlusive or near occlusive, whatever baseline difference in coronary flow exists between the right and the left arteries would not necessarily matter.
The argument against using thrombolysis in RCA territory infarct is generally limited to patients with isolated inferior wall infarct. In such cases, the prognosis is good and it is hard to demonstrate mortality benefit for thrombolysis. Given that the risk of intracranial hemorrhage is unchanged, it is felt that in such patients the risk/benefit ratio does not obviously support the use of thrombolysis.
Also FYI, the first post of your home page has a remote date (2008) and this is a bit confusing 🙂
Michel Accad, MD