* Two cardiologist surveys point to success for LCZ696
* Novartis sees drug selling $2-5 bln a year or more
* Clinical trial data due at medical meeting Aug. 31
LONDON, Aug 5 (Reuters) - Expectations are building for a new heart failure drug from Novartis viewed as a likely multibillion-dollar seller, with two surveys of cardiologists published on Tuesday highlighting its potential.
A large clinical trial with LCZ696 was stopped early in March because the benefit to patients was overwhelmingly positive. Just how good the drug was will be disclosed at a medical meeting in Spain at the end of this month.
The size of the benefit is critical in determining how widely LCZ696 might be used to treat millions of patients with chronic heart failure, in which the heart struggles to pump blood around the body efficiently.
There has been little progress in treating the condition in recent years, leaving doctors dependent on old generic medicines which do not work that well.
Novartis is looking to LCZ696 to revive its fortunes as the blood pressure pill Diovan faces generic competition. The forthcoming detailed data is viewed as the most important catalyst for the stock over the remainder of 2014.
Heart experts polled separately by Deutsche Bank and Cowen both predicted Novartis's so-called PARADIGM-HF trial would show an important reduction in the risk of cardiovascular death among patients taking LCZ696 versus those on a standard heart drug, known as an ACE inhibitor.
A survey of 25 cardiologists by Cowen found that, on average, they expected the relative risk reduction in the trial would be 23 percent, as measured by heart failure hospitalisations and mortality.
A similar-sized poll by Deutsche Bank concluded that a 15 percent or more benefit would be highly relevant and a result above 20 percent could prompt use of the drug in patient groups beyond those selected for the PARADIGM-HF trial.
Novartis has said LCZ696 could achieve annual peak sales of between $2 billion and $5 billion, or more.
But the company has also cautioned investors not to expect too much in terms of risk reduction, since LCZ696 was tested against an active drug, rather than a dummy pill - and the ACE inhibitor used as a control had already produced a risk reduction of 16 percent over a placebo in earlier tests.
"We don't know what the numbers look like but if you did have a 15 to 16 percent reduction in relative risk ... that would be a number that translates to a pretty darn big drug," Novartis Chief Executive Joe Jimenez said in a post-results call last month.
Full results on LCZ696 will be presented in Barcelona on Aug. 31 at the annual meeting of the European Society of Cardiology, which has already described the study as a highlight of the event.
While forecasts have been climbing, the consensus for sales of LCZ696 in 2018 - three years after its expected launch - is only about $900 million, according to Thomson Reuters Pharma.
If the results presented in Barcelona are as good as hoped, those estimates are likely to climb, although analysts remain divided as to how big the drug could be.
Cowen predicts sales of $1.25 billion in 2020 and a potential of $3-6 billion, depending on the clinical results. Deutsche Bank believes it could eventually sell as much as $10 billion, assuming it works across two broad groups of heart failure patients.
While the PARADIGM-HF study targeted patients with so-called reduced ejection fraction, affecting the left side of the heart, Novartis is also starting a trial in a similar-sized group with preserved ejection fraction.
Others are a lot more wary. Morgan Stanley argued last month that Novartis might need to show a significantly larger risk reduction of around 30 percent to really convince doctors and healthcare providers to use its new medicine, which could cost $2,000-2,500 a year. (Editing by David Clarke)