BackgroundThe cardiovascular complications of cancer therapeutics are the focus of the burgeoning field of cardio‐oncology. A common challenge in this field is the impact of cancer drugs on cardiac repolarization (ie, QT prolongation) and the potential risk for the life‐threatening arrhythmia torsades de pointes. Although QT prolongation is not a perfect marker of arrhythmia risk, this has become a primary safety metric among oncologists. Cardiologists caring for patients receiving cancer treatment should become familiar with the drugs associated with QT prolongation, its incidence, and appropriate management strategies to provide meaningful consultation in this complex clinical scenario.Methods and ResultsIn this article, we performed a systematic review (using Preferred Reporting Items of Systematic Reviews and Meta‐Analyses (PRISMA) guidelines) of commonly used cancer drugs to determine the incidence of QT prolongation and clinically relevant arrhythmias. We calculated summary estimates of the incidence of all and clinically relevant QT prolongation as well as arrhythmias and sudden cardiac death. We then describe strategies to prevent, identify, and manage QT prolongation in patients receiving cancer therapy. We identified a total of 173 relevant publications. The weighted incidence of any corrected QT (QTc) prolongation in our systematic review in patients treated with conventional therapies (eg, anthracyclines) ranged from 0% to 22%, although QTc >500 ms, arrhythmias, or sudden cardiac death was extremely rare. The risk of QTc prolongation with targeted therapies (eg, small molecular tyrosine kinase inhibitors) ranged between 0% and 22.7% with severe prolongation (QTc >500 ms) reported in 0% to 5.2% of the patients. Arrhythmias and sudden cardiac death were rare.ConclusionsOur systematic review demonstrates that there is variability in the incidence of QTc prolongation of various cancer drugs; however, the clinical consequence, as defined by arrhythmias or sudden cardiac death, remains rare.

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Objective To examine the safety of using aliskiren combined with agents used to block the renin-angiotensin system.Design Systematic review and meta-analysis of randomised controlled trials.Data sources Medline, Embase, the Cochrane Library, and two trial registries, published up to 7 May 2011.Study selection Published and unpublished randomised controlled trials that compared combined treatment using aliskiren and angiotensin converting enzyme inhibitors or angiotensin receptor blockers with monotherapy using these agents for at least four weeks and that provided numerical data on the adverse event outcomes of hyperkalaemia and acute kidney injury. A random effects model was used to calculate pooled risk ratios and 95% confidence intervals for these outcomes.Results 10 randomised controlled studies (4814 participants) were included in the analysis. Combination therapy with aliskiren and angiotensin converting enzyme inhibitors or angiotensin receptor blockers significantly increased the risk of hyperkalaemia compared with monotherapy using angiotensin converting enzymes or angiotensin receptor blockers (relative risk 1.58, 95% confidence interval 1.24 to 2.02) or aliskiren alone (1.67, 1.01 to 2.79). The risk of acute kidney injury did not differ significantly between the combined therapy and monotherapy groups (1.14, 0.68 to 1.89). ConclusionUse of aliskerin in combination with angiotensin converting enzyme inhibitors or angiotensin receptor blockers is associated with an increased risk for hyperkalaemia. The combined use of these agents warrants careful monitoring of serum potassium levels. IntroductionBlockade of the renin-angiotensin system using angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers has been advocated for the management of congestive heart failure, hypertension, and proteinuria.1 2 The opportunity to block the renin-angiotensin system at multiple foci has a compelling biological rationale but may be associated with significant toxicity. [3][4][5][6] Direct inhibition of renin-the most proximal aspect of the renin-angiotensin system-became clinically feasible from 2007 with the introduction of aliskiren (Rasilez; Novartis Pharmaceuticals, Switzerland). Aliskiren has been shown to be efficacious for the management of hypertension, congestive heart failure, and proteinuria either as monotherapy 7 8 or in combination with ACE inhibitors or angiotensin receptor blockers. [9][10][11][12] In Ontario, Canada (estimated population 13 million), the use of aliskiren has increased from 56 603 individual prescriptions in 2009 to 119 891 in 2010. 13The publication of the Ongoing Telmisartan Alone and in Combination with Ramipril Global Endpoint Trial (ONTARGET) highlighted the danger of dual inhibition of the renin-angiotensin system, reporting an increased risk of acute Correspondence to: Z Harel harelz@smh.ca Extra material supplied by the author (see