Acute coronary syndrome is primarily a disease of blood vessel , which perfuses the heart. It can even be a disorder of blood, often called vulnerable blood which predispose for intra- coronary thrombus .
Mind you , heart is an innocent bystander ! to the onslaught of coronary atherosclerosis !
Hence , we often use two terminologies .
CAD : Pure vascular (Coronary ) disease without any structural and functional impairment of heart ( No Angina, No myocardial damage ) Most of the asymptomatic plaques , non flow limiting lesions, incidentally detected by the modern coronary imaging gadgets fall in this category.
When does CAD becomes CAHD ?
CAHD : Coronary artery heart disease .Here not only the coronary artery is diseased , but it has it’s mission fulfilled ie target organ either damaged structurally (STEMI, NSTEMI ) or functionally (EST positive , Chronic stable angina CSA )
Does the heart does any wrong to suffer from Acute coronary syndrome ?
No, it is simply not .The fault lies in one or more of the following .Generally at-least two these factors are enough to impede blood flow ) . They combine to produce an ACS.
- Blood defect
- Vessel wall defect
- Slowing of flow (Stasis)
This is called as Virchow’s triad suggested over 100 years ago . Still valid in the era of per cutaneous aortic valve implantation.
* The concept of de-linking disorders of coronary vascular disease from myocardial disease is vital in understanding the implications of current modalities of treatment.
Even though we PCIs target the culprit ie blood vessel , it need to realised , we always fall short of real target . . .namely the heart . In coronary interventions the catheters and wires roam around superficially over the heart and they never even touch the heart .This is the reason PCIs are struggling to prove it’s worthiness over medical therapy in many CAHD patients , which can reach deep into the vessel, heart and even every individual cells of heart.
Many (or . . . is it most ?) Interventional cardiologists have a bad reputation for ” failing to look look beyond the lesion” . It is estimated a vast number of cathlabs and CABG theaters worldwide are engaged in futile attempt to restore coronary artery patency after a target organ damage is done .This is akin to building flyovers to dead and closed highways .
Salvaging a coronary artery and reliving a coronary obstruction is an entirely unrelated and futile exercise to a patient who has a problem primarily in musculature .
The much debated concept of documenting myocardial viability , before revascularisation died a premature death as the concept by itself , was not viable commercially . (Viability studies , tend to tie down the hands of device industry further , some interventional cardiologists began to see this concept as an interference to their freedom to adventure )
Of-course , now we have other parameters phenomenon like FFR estimation by Doppler , epicardial -myocardial dissociation, slow flow , no re-flow are gaining importance.
Final message
ACS is primarily a disease of blood vessel but it’s impact is huge on heart. We need to look beyond the lesion .Restoring a blood vessel patency to an ailing organ (Heart ) is not synonymous with total cardiac intervention and protection . There is lot more to cardiac physiology other than it’s blood flow. Heart muscle is a too complex organ to be controlled by few balloons and wires which beat around the bush.
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Dr.S.Venkatesan MD 