Conditions & Treatments: Symptoms, Causes and Risk Factors, Diagnosis, Treatment

Acute Coronary Syndromes - Treatments

The goal of treatment for patients with ACS is to reduce or prevent further thrombus formation at the site of plaque rupture and relief of ischaemia by reducing the demand of heart muscle or increase the blood supply by unblocking the artery blockage.

Unstable angina and NSTEMI
The presentation and prognosis of unstable angina and NSTEMI are similar and therefore the treatment for both is the same. The only difference is that in NSTEMI, there is damage of a portion of heart muscle with abnormal increased levels of cardiac markers detected in the blood.

Reducing and preventing formation of thrombus

After the plaque ruptured in the artery, platelet plays a vital role in initiating the clot. If there is no contraindication, you will be given 2 types of antiplatelet agents to prevent further platelet deposition at the ruptured plaque. These 2 agents are also required when there is intention to perform coronary stenting (see below). Anti-coagulation (heparins) will also be given to dissolve the clot that has formed on the ruptured plaque. This is usually given as injection under the skin (subcutaneously) or occasionally as an infusion into a vein (intravenously). Please see Table 1 for various combinations of antiplatelet agents and anti-coagulation. Both antiplatelet and anticoagulation agents have been proven to reduce heart attack and death in patients with ACS.

Reducing demand and improving supply

At the beginning of your admission, you may be required to continuously rest in bed to reduce the demand of your heart until your condition become more stable. Oxygen will be given to improve oxygenation of the blood, thus increasing the oxygen supply to the heart. Medications like beta-blockers will be prescribed to slow down the heart rate, which reduces the demand of the heart muscle, while nitrates (IV or oral) dilate the artery to improve the blood supply to the heart muscle.

The most effective method to improve blood supply, however, is to unblock the artery, which can be done by either coronary angioplasty (inserting stents via the wrist or groin) or CABG, especially in patients with extensive or high risk blockages. (Figure 4 – TIMI risk score) In high risk patients, a coronary angiography is suggested to be performed within 24 hours to check the number and severity of the blocked coronary artery. Your doctor who performs the coronary angiography will advise you what the best treatment option is. In general, coronary stenting can be performed safely in patients with 1 or 2 blocked arteries but in patients with all 3 blocked arteries (especially patients with diabetes mellitus) CABG may be a better option.

STEMI

The treatment of STEMI is completely different from unstable angina and NSTEMI, in terms of urgency and treatment options. In STEMI, the artery is completely occluded by thrombus and the heart muscle supplied by that artery will be irreversibly damaged if not opened within 6 to 12 hours. The longer the artery remains occluded the more extensive the damage to the heart muscle and the speed of treatment in STEMI is therefore crucial.

There are 2 treatment options for STEMI – powerful clot buster (thrombolysis) or coronary stenting (primary angioplasty). Although intravenous thrombolysis is easy and fast, the success rate of opening the artery in STEMI is only 50 to 60%. It also carries the inherent risk of bleeding complications, especially intracranial haemorrhage, which is usually fatal. In NHCS, all patients with STEMI are considered for primary angioplasty if there is no contraindicated. The occluded artery is usually opened successfully in 90% of patients by inserting a stent at the site of ruptured plaque. Primary angioplasty in large centers and experienced operators has been shown to improve outcomes compared to intravenous thrombolysis. However, primary angioplasty for patients with STEMI needs to be performed immediately, preferably within 60 to 90 minutes of admission to ED, in order to achieve maximum benefit.

While in ED, patient will be given loading doses of 2 antiplatelet agents. Once the informed consent for primary angioplasty is given, the patient is transferred to cardiac catherisation laboratory where the primary angioplasty team members will immediately perform coronary angiography and stenting if appropriate. Occasionally stenting may not be required or possible and in some cases urgent coronary artery bypass surgery is necessary.

After the procedure (usually 60 to 90 minutes depending on the complexity of the lesions) the patient will be admitted to coronary care unit (CCU) for monitoring of heart rhythm and blood pressure. Patients with STEMI may develop life threatening rhythm and complications after heart attack. Early detection and treatment of these complications saves lives.

Similar to unstable angina and NSTEMI, medications to decrease the demand of heart muscle (beta-blocker) and improve blood supply to heart muscle (nitrates) will be given.