This is a very commonly asked question.

The answer is not entirely known but over the past several years we've had some insights into it. Over time with accumulation of data from clinical trials, it's fairly clear that ACE inhibitors have a greater quantity of data in patients with heart failure had established coronary artery disease in terms of their role in cardioprotection. And so, most contemporary guidelines will position ACE inhibitors ahead of angiotensin receptor blockers for the management of hypertension and to confer cardioprotection in this patient population. Because of studies like ONTARGET and VALIANT, angiotensin receptor blockers have been increasingly viewed as similar if not superior to ACE inhibitors in terms of cardioprotection. In terms of patients with chronic kidney disease particularly due to diabetes, angiotensin receptor blockers have long been associated with preservation of renal function. Of course, these patients are also at risk for cardiovascular disease and so there was temptation to preferentially use ACE inhibitors in this group as well. Once again, now that we have studies such as, ONTARGET and VALIANT, treating patients who have chronic kidney disease with angiotensin receptor blockers is particularly attractive because of the low incidence of side effects with these medications and because these studies have suggested that the cardioprotection seen with ACE inhibitors also applies to this drug class.

Therefore, in my own practice I actually adopt both medications and use them in an evidence-based fashion depending on the comorbidities. So in patients with primarily cardiovascular disease, without renal disease, I tend to use ACE inhibitors and in those patients without a great burden of cardiovascular disease but more significant renal disease (particularly diabetic renal disease), I tend to use angiotensin receptor blockers 1st in these patients. This practice can be depicted in the figure below: