Acute coronary syndromes ( ACS ) constitute a range of conditions as unstable angina and myocardial infarction. This happens due to sudden reduction in blood flow to the heart , usually caused by the rupture of an atherosclerotic plaque within the wall of a coronary artery , and may cause the formation of a clot ( NICE 2014 )
How common – ACS is often the first presentation of coronary artery disease ( CAD ) IHD is the number one cause of death , disability and human suffering globally IHD ( Ischaemic heart disease ) is the most common form of heart disease and the single most important cause of premature death worldwide despite major breakthroughs in management ( Medical Statics Unit , Sri Lanka , 2013 ) IHD is the greatest single cause of mortality and loss of disability-adjusted life years ( DALYs) worldwide , and they account for about 7 million deaths and 129 million DALYs annually ( Lozano R et al and Murray CJ et al ) WHO has reported that in 2013 , IHD was responsible for 8.1 million deaths worldwide in 2013 ( 95 % uncertainty interval , 7.3-8.8 million ) and there was an increase of 42 % in the number of IHD deaths since 1990 In developed countries the incidence rates of ACS is decreasing but they remain a major cause of premature deaths About 25 % of people die before reaching hospital in ST elevation MI ( BMJ ) In developed countries IHD is still responsible for about 1/3rd of all deaths in people older than 35 yrs In the UK every 4 minutes someone is admitted to hospital with a heart attack or chest pain – leading to over 150 , 000 hospitalizations / year Prevalence increases with age for both men and women
What happens – Most cases are due to thrombosis developing on a culprit atherosclerotic plaque this causes obstruction to flow in the coronary artery lumen with downstream ischaemic myocardial injury Other rare causes include ( STEMI ) - spontaneous coronary artery dissection - coronary arteritis - coronary emboli - coronary spasm - compression by myocardial bridges Autopsy reports have shown than 70% to 80 % of coronary thrombi occur at sites where the fibrous cap of coronary artery plaque has ruptured – thrombus can extend into the plaque and into the lumen and can travel upstream from the site of rupture.
Risk factors –
Non-modifiable -Age ( increases with age ) Sex ( see more often in men ) Family history is a major cause risk factor for CAD ( coronary artery disease )
Modifiable – Hypertension elevated serum cholesterol Type II DM Smoking Obesity and sedentary lifestyle.
Myocardial infarction definition – Definition used by NICE ( 2020 ) for Myocardial Infarction says ‘ a rise in biomarkers ( preferable cardiac troponin ) with at least 1 value above the 99th percentile of the upper reference limit / and or a fall in cardiac biomarkers , together with atleast 1 of the following symptoms of ischaemia new or presumed new significant ST-segment -T wave changes or new LBBB pathological Q wave changes in ECG imaging evidence which shows new loss of viable myocardium or new regional wall motion abnormality identification of an intracoronary thrombus by angiography.
ST elevation MI – Here the atheromatous plaque has ruptured causing thrombosis and myocardial ischaemia which causes irreversible necrosis and often long term complications ECG will show persistent ST elevation ( STE ) The ischaemia is transmural causing myocardial injury or necrosis Raised cardiac biomarkers confirm STEMI STE is the single best immediately available pointer of acute complete coronary artery occlusion indicating a significant region of injured myocardium at imminent risk of irreversible infarction The aim is to diagnose promptly and commence reperfusion therapy as soon as possible – TIME IS MUSCLE Reperfusion therapy should be offered to eligible patients with STEMI and symptoms onset within the previous 12 hours.
NonST ACS – Unstable angina ( UA ) shares similar patient characteristic , pathophysiology and outcome as NSTEMI Presentation may range from patients free of symptoms at presentation to those with ongoing ischaemia , haemodyamic or electrical instability or even cardiac arrest NSTEMI is diagnosed when there is evidence of acute myocardial necrosis in association with a clinical setting consistent with MI ( ie biochemical evidence ) UA is diagnosed when patients have ischaemic symptoms at rest or with minor exercise with no evidence of myocardial necrosis Patient may have a previous h/o stable angina , previous MI and or myocardial revascularization UA may represent an acceleration ECG may show changes as - persistent ST segment depression ( if ECG is obtained during pain ) - transient ST- segment elevation - deep symmetrical > 2mm T wave inversions Mortality from NSTE-ACS has declined steadily with improved acute treatment.
Primary percutaneous coronary intervention ( PCI )- PCI is the preferred option and trial have shown clinical benefit in terms of mortality , stroke and re-infarction You may hear terms like -Call-to-balloon time , 1st medical contact to balloon time - Door to balloon time these are targets set by national programme to reduce the time needed to perform PCI and improve outcomes PCI beyond 24 hrs is not beneficial Post STEMI drugs include - dual antiplatelet therapy ( DAPT ) usually aspirin lifelong + prasugrel or ticagrelor or clopidogrel - statins ( for e.g atorvastatin 80 mg ) - beta blocker - ACE inhibitor Other medication based on presentation and clinical indications Lifestyle interventions
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