Eligible for inclusion in the review were randomised placebo-controlled trials with a mean duration of at least 12 months of tissue selective angiotensin-converting enzyme inhibitors (ramipril, perindopril, quinapril, or trandolapril) in patients with cardiovascular disease. Eligible patients were required to have either had documented echocardiographic evidence of normal left ventricular systolic function (left ventricular ejection fraction more than 40%) or had no clinical symptoms of chronic heart failure.
Outcomes of interest were incidence of all-cause mortality, cardiovascular disease mortality, fatal and non-fatal myocardial infarction, stroke, need for invasive coronary revascularisation such as percutaneous transluminal coronary angioplasty or coronary artery bypass graft surgery, hospitalisation for angina, and occurrence of new-onset diabetes mellitus.
Mean age (58 to 66 years) and percentage of female participants (14.5 to 27.5%) were similar in the included trials. However, the trials differed significantly in important baseline characteristics such as percutaneous transluminal coronary angioplasty (range 18.4 to 93%); stroke (3.4 to 10.8%); peripheral vascular disease (7.1 to 42.3%); diabetes (11.8% to 38.9%); the use of concomitant medications such as lipid lowering drugs (0.1 to 70%); and in open label angiotensin-converting enzyme inhibitor use in placebo groups (8.1 to 23%).
Two authors independently conducted the searches. It was not clear if the statement 'differences were resolved by discussion' applied to study selection.