For patients with HFrEF, diuretics are also prescribed to manage fluid retention and symptoms. There is a substantial evidence base to support the use of medicines to reduce both mortality and morbidity. In the absence of contraindications, all patients should be prescribed a combination of:

• An angiotensin converting enzyme inhibitor (ACEI). An angiotensin receptor blocker (ARB) licensed for heart failure can be used as an alternative if side effects
  such as ACEI cough occur
• A beta-blocker licensed for heart failure – in the UK this is bisoprolol, carvedilol or nebivolol.

These medicines are introduced at low doses and carefully up titrated, at intervals of not less than two weeks, to the maximum dose or the maximum tolerated dose for the patient.

For ACEI/ARB titration the renal function is checked one to two weeks after each dose increase to ensure renal stability and to monitor for electrolyte disturbances, in particular hyperkalaemia (high potassium) or hyponatraemia (low sodium). Blood pressure is also checked as hypotension or postural hypotension may be dose limiting. 

Beta-blockers for patients in sinus rhythm (the normal heart rhythm) are titrated upwards, aiming for a resting heart rate of around 60 beats/minute. For patients in atrial fibrillation the target heart rate is less clearly defined and generally the dose of beta-blocker is increased to achieve a heart rate of less than 110 beats/minute on gentle exertion. As with ACEI/ARB, the blood pressure may be a dose-limiting factor.

A medication review is a good way of identifying patients where suboptimal doses are prescribed and referring these patients to their GP or heart failure team, depending on local services, to ensure that the treatment is optimised.

If an HFrEF patient is still symptomatic despite an ACEI/ARB and beta-blocker combination, the next step is the addition of a mineralocorticoid receptor antagonist (MRA). The choices are either spironolactone or eplerenone. As these medicines also cause potassium retention, co-prescription with an ACEI/ARB requires careful monitoring of renal function and electrolytes. It is recommended that a blood test is undertaken to check renal function and electrolytes one week after starting treatment (or any dose increase) and then monthly for three months and as a minimum every six months thereafter.