The approval for heart failure was based on results of the Metoprolol CR/XL® (Controlled Release) Randomised Intervention Trial in Heart Failure (MERIT-HF), the largest heart failure trial ever completed (3,991 patients: 1,990 in Toprol-XL treatment arm) evaluating the efficacy of a beta-blocker. The trial was terminated earlier than expected by the Independent Safety Committee due to a significant reduction in mortality in patients treated with Toprol-XL® as compared to placebo. In MERIT-HF, the use of Toprol-XL® in combination with Ace Inhibitors, diuretics and digitalis resulted in an all-cause mortality of 7.3 percent compared to 10.8 percent in the placebo group. This is a risk reduction of 34 percent. The risk of all-cause mortality plus all-cause hospitalisation was reduced by 19 percent (placebo: 38 percent Toprol-XL: 32 percent).

In MERIT-HF, the risk of cardiovascular mortality was reduced by 38 per cent (placebo: 10.1 percent Toprol-CL: 6.4 percent), and the risk of death from worsening heart failure was reduced by 49 per cent (placebo: 2.9 percent Toprol-XL:1.5 percent). All mortality risk reductions were statistically significant. The data on all-cause mortality plus all-cause hospitalisation and the data on all-cause mortality plus heart failure hospitalisation showed consistent effects in the overall study population and subgroups including women and the US population. However, the US subgroup (n=1071) and women (n=898), overall mortality and cardiovascular mortality appeared less affected.

MERIT-HF included significant numbers of patients across a wide spectrum of heart failure severity with the majority of patients in the NYHA Class II (41 percent) and Class III (55 percent). The study found that the addition of Toprol-XL® to standard therapy, showed benefit in patients in NYHA Classes II and III. The trial also showed improvements in heart failure -- related mortality and heart failure -- related hospitalisations, and NYHA functional class.

Toprol-XL® (marketed outside of the US as Seloken ZOC®) is the most widely prescribed branded beta-blocker in the world.

AstraZeneca is a major international healthcare business engaged in the research, development, manufacture and marketing of ethical (prescription) pharmaceuticals and the supply of healthcare services. It is one of the top five pharmaceutical companies in the world with healthcare sales of $15 billion and leading positions in cardiovascular, gastrointestinal, oncology, anaesthesia including pain management, central nervous system (CNS) and respiratory products.