Some of what Peter de Leeuw states is obvious. It is well known that co-administration of two blockers of the renin angiotensin system may cause renal dysfunction and hyperkalaemia. Even one blocker may do so. That is not the point. What matters clinically is whether these adverse effects are offset by a greater clinical benefit and whether the net benefit-risk ratio is favourable.

Professor de Leeuw also makes an incorrect statement in relation to patients with left ventricular dysfunction. In patients with heart failure and a reduced left ventricular ejection fraction, dual renin-angiotensin system blockade with an angiotensin converting enzyme (ACE) inhibitor and angiotensin receptor blocker (ARB) results in clear net benefit and is recommended in guidelines.1-3 The benefit-risk balance is not favourable in other patients. The net effect of aliskiren, either on its own or in combination with an ACE inhibitor or ARB, in patients with heart failure (with or without diabetes) is at present unknown but under investigation in clinical trials.4,5

1. Cohn JN, Tognoni G; Valsartan Heart Failure Trial Investigators. A randomized trial of the angiotensin-receptor blocker valsartan in chronic heart failure. N Engl J Med 2001; 345: 1667-75.
2. McMurray JJ, Ostergren J, Swedberg K, Granger CB, Held P, Michelson EL, Olofsson B, Yusuf S, Pfeffer MA; CHARM Investigators and Committees. Effects of candesartan in patients with chronic heart failure and reduced left-ventricular systolic function taking angiotensin-converting-enzyme inhibitors: the CHARM-Added trial. Lancet 2003; 362: 767-71.
3. Dickstein K, Cohen-Solal A, Filippatos G, McMurray JJ, Ponikowski P, Poole-Wilson PA, Strömberg A, van Veldhuisen DJ, Atar D, Hoes AW, Keren A, Mebazaa A, Nieminen M, Priori SG, Swedberg K; ESC Committee for Practice Guidelines (CPG). ESC guidelines for the diagnosis and treatment of acute and chronic heart failure 2008: the Task Force for the diagnosis and treatment of acute and chronic heart failure 2008 of the European Society of Cardiology. Developed in collaboration with the Heart Failure Association of the ESC (HFA) and endorsed by the European Society of Intensive Care Medicine (ESICM). Eur J Heart Fail 2008; 10: 933-989.
4. Krum H, Massie B, Abraham WT, Dickstein K, Kober L, McMurray JJV, Desai A, Gimpelewicz C, Kandra A, Reimun B, Rattunde H, Armbrecht J, on behalf of the ATMOSPHERE Investigators. Direct Renin Inhibition in Addition to or as an Alternative to ACE Inhibition in Patients with Systolic Chronic Heart Failure: Rationale and Design of the Aliskiren trial to Minimize Outcomes in Patients with Heart failure. (ATMOSPHERE) study. Eur J Heart Fail 2011; 13: 107-14.
5. Gheorghiade M, Albaghdadi M, Zannad F, Fonarow GC, Böhm M, Gimpelewicz C, Botha J, Moores S, Lewis EF, Rattunde H, Maggioni A; ASTRONAUT investigators and study coordinators. Rationale and design of the multicentre, randomized, double-blind, placebo-controlled Aliskiren Trial on Acute Heart Failure Outcomes (ASTRONAUT). Eur J Heart Fail 2011; 13: 100-6.

Competing interests: Member of the Executive Committees for CHARM-Added (candesartan), EMPHASIS-HF (eplerenone) and ATMOSPHERE (aliskiren) trials in heart failure. Speaker fees from AstraZeneca/Takeda (candesartan), Pfizer (eplerenone) and Novartis (aliskiren).