Nothing in this world is black and white. In fact, most events are in between . The irony is , our brain always wants to view things in two distinct entities !
- Success or failure
- Beautiful or ugly
- Good or bad
- Win or lose,
- Rich and poor etc . . . etc
So it is no surprise ! cardiologists also travel in the same boat !
They classified the events after thrombolysis into two dogmatic categories . Successful thrombolysis or failed thrombolysis . . . as if no other event can occur in between .
Traditionally 50% regression of ST segment is called successful . What about 30% and 40 % ST regression ?
Further , there is an important caveat in the timing, as we traditionally assess , 90 minutes of thrombolysis .
Consider the following situation :
- Thrombolysis is failed at 90 minutes, but succeeds at 120/180 minutes ?
- Is 50 % ST regression at 180 minutes is as bad or as good as 25 % regression at 90 minutes ?
- How to label a patient who is extremely comfortable in spite of ECG criteria of failed thrombolysis ?(Surprisingly this situation is fairly common !)
So, without finding answers to some critical questions , we have defined the success of thrombolysis with half baked data .
This is exactly , is the reason we are unable to do a valid study on failed thrombolysis, rescue PCI etc . We know the results of rescue PCI , always been contradictory to the general logic !
It is estimated a substantial number of STEMI patients following thrombolysis fall into a category of partially successful thrombolysis implying partial restoration of blood flow and salvage. The correct definition for successful thrombolysis and reperfusion should be at the myocardial mass level , and not at the level of coronary artery.The ECG is the best available indicator.
Implication for having a poor definition of failed thrombolysis
It is not a rare sight to wheel in , a patient to a cath lab with label of failed thrombolysis dangling in his neck who is clinically stable (Has a less than required 50% ST regression , but a definite, favorable trend with a 30 % ST regression at 90 minutes )
How many cardiologists will be willing to abort a CAG/PCI , as a repeat ECG just before puncturing in the cath lab reveals successful thrombolysis ? (little delayed though !)
If only we have better methods to risk stratify patients following thrombolysis , we can avoid
- Huge costs incurred
- Expected and unexpected hazards of doing an emergency intervention in an adequately salvaged STEMI
- Hundreds of cardiology man hours can be saved for better purposes .
Final message
Classifying thrombolyis into success or failure is a skewed way of looking at this important issue .
It is an irony , cardiologists often triage LV dysfunction , valve disease , cardiac failure etc into 4 grades ( minimal , mild , moderate or severe ) . It is still a mystery , why thrombolysis is never graded like that , and it is always considered as all or none phenomenon !
There is a substantial number of patients with partially successful ( or shall we call partially failed !) thrombolyis .This group must be given adequate attention or inattention . There is a urgent need for a through review of how we look at the post thrombolysis status . It is better to use the newer imaging modalities like PET/MRI more liberally to identify exact sub group of failed thrombolysis who will benefit form revascularisation .
Dr.S.Venkatesan MD 