Assessment of the patient with suspected Acute Coronary Syndrome (ACS) is based on clinical presentation, serial ECG changes and high sensitivity cardiac troponin (hs-cTn I, hsT) measurements.

At Frimley Park we have adopted the 0 h/3 h algorithm for ACS patients presenting without ST elevation. 0 h/3 h refers to blood samples taken at 0 (baseline) and 3 hours, the time from the first blood test.

On August 22, 2022, the high sensitivity cardiac troponin (hs-cTn I, hs T) assay will change from the Siemens to the Abbott Alinity assay across Surrey. Reference ranges will change in line with the manufacturer’s recommended cut-offs, and an important change to current practice will be sex-specific cut offs. In practice, this means 2 separate algorithms for men and women. The absolute rule-in cut-off will change from 120 ng/L to 64 ng/L for both sexes. The 99th centile cut-off of <47 will be replaced by <16 (female) and <34 (male).

Patients with ST elevation on their ECGs should be managed according to PPCI guidelines for STEMI.

Patients are at high risk of NSTEMI (RULE IN) if:

• they have dynamic ECG changes, hsT ≥64 at 0 h or 3 h,

OR IN WOMEN:

• an increase in hsT (∆ hsT) over 3 hrs >20% IF their 0h hsT was ≥16, or
• an increase in hsT (∆ hsT) over 3 hrs >50% IF their 0h hsT was <16 AND their 3h hsT was >16.

OR IN MEN:

• an increase in hsT (∆ hsT) over 3 hrs >20% IF their 0h hsT was ≥34, or
• an increase in hsT (∆ hsT) over 3 hrs >50% IF their 0h hsT was <34 AND their 3h hsT was ≥34.

They should be admitted to a Cardiology bed and started on ACS treatment. The ACS Nurse (bleep 5777) should be informed between 9am and 5pm (Mon to Fri).

If the patient has ongoing chest pain, haemodynamic instability, or dynamic ECG changes, please discuss with the on-call cardiologist.

Patients are at low risk of NSTEMI (RULE OUT) if:

• they are well, have atypical symptoms, normal ECGs (or have minor fixed ECG changes)

AND IN WOMEN:

• have a hsT<16 at 0 h if they have had chest pain for >6hrs OR a hsT <16 at 3 h if duration of chest pain at presentation (0 h) was <6hrs.

OR IN MEN:

• have a hsT<34 at 0 h if they have had chest pain for >6hrs OR a hsT <34 at 3 h if duration of chest pain at presentation (0 h) was <6hrs.

Patients falling in between these categories should be placed in a third INTERMEDIATE category.

For patients in the intermediate category, the GRACE Score should be calculated using the calculator at this website: https://www.outcomes-umassmed.org/risk_models_grace_orig.aspx

If the patient is pain free and GRACE Score <140, ACS is unlikely. Discharge patient with reassurance, giving backstop advice to re-attend if pain recurs.

If GRACE Score >140 and no other cause identified, refer to fhft.RASACfph@nhs.net to receive F/U phone assessment by Chest Pain Nurse.

CAVEATS: The algorithm should only be used in conjunction with all available clinical information, including detailed assessment of chest pain characteristics and ECG. The algorithm applies to all patients irrespective of chest pain onset. As late increases in cardiac troponin have been described in <1% of patients, serial hsT testing may be pursued if the clinical suspicion remains high or if the patient develops recurrent chest pain. In all patients with severe chest pain, think about the possibility of aortic dissection.

Intermediate and high risk ACS patients (> 3% risk of 6 month mortality on GRACE score) must considered for coronary angiography +/- PCI within 72 hrs. Very high risk cases (> 6% risk) may benefit from an early procedure within 24 hrs.

See algorithm below.

After loading with Aspirin 300mg od and Clopidogrel 300mg od (unless the patient is on the PPCI pathway in which case 600mg), Aspirin 75 mg od should continue for life.

Clopidogrel 75 mg od should continue for 12 months after the event unless specified by the cardiologist.

The cardiologist may choose to use the following instead of Clopidogrel:

• Prasugrel (initially 60mg for one dose, then 10mg od (or 5mg if weight <60kg or age >75 years) usually up to 12 months). Loading dose not to be given until time of PCI.
• OR Ticagrelor (initially 180mg for one dose, then 90mg bd usually up to 12 months).

Consider gastric protection with Omeprazole or Lansoprazole if at risk of peptic ulceration, especially if age >75 years or on triple therapy (an anticoagulant and DAPT).

Start Fondaparinux 2.5mg sc od unless already on Warfarin, DOAC, weight <50kg, or patient has significant renal impairment (CrCl <20 mL/min).

If patient is on Warfarin, aim for an INR between 2 and 2.5.

If on a DOAC, refer to bridging guidelines.

Administer sublingual GTN if BP allows.

Patients with ongoing chest pain may receive Morphine IV PRN given with anti-emetic such as Metoclopramide 10mg IV (Avoid Metoclopramide in patients with Parkinson’s disease).

While waiting for coronary angiography, patients may be started on a GTN IV infusion if they have ongoing chest pain. These patients should be managed on CCU ideally and the on call cardiologist informed if the GTN requirement is increasing.

Patients should be started on long-term ACEI therapy as soon as they are haemodynamically stable.

First-line Ramipril 1.25mg OD, titrate up if appropriate.

Do not start if patient has renal failure or systolic BP<90.

Start Bisoprolol 1.25mg OD and titrate up if appropriate unless:

• Bradycardia<50bpm
• Second or third-degree heart block
• Cardiogenic shock
• History of brittle asthma

Alternatively, start Metoprolol 25mg BD.

All patients with ACS should be commenced on a statin within the first 24 hours.

First-line Atorvastatin 40mg nocte (80mg in STEMI patients). Do not switch if already on Rosuvastatin.

Consider lower dose for low risk NSTEMIs or older patients and titrate up if tolerated.

Monitor/review patients receiving drugs with potential to interact (Cyclosporin, protease inhibitors, Diltiazem, Amiodarone, Verapamil). Please see BNF for a complete list.

Hold if patient prescribed Clarithromycin or Erythromycin.

1. 2020 ESC Guidelines for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation: The Task Force for the management of acute coronary syndromes in patients presenting without persistent ST-segment elevation of the European Society of Cardiology (ESC), European Heart Journal, August 2020
2. Acute coronary syndromes NICE guideline [NG185], November 2020
3. Hayley Sharrod-Cole , Clare Ford. Multicenter Evaluation of a High-Sensitivity Troponin I Assay and Verification of an Early Rule-Out Algorithm. J Appl Lab Med 2019; 4: 95-100
4. Kimenai, D.M., Lindahl, B., Jernberg, T. et al. Sex-specific effects of implementing a high-sensitivity troponin I assay in patients with suspected acute coronary syndrome: results from SWEDEHEART registry. Sci Rep 10, 15227 (2020).