April 28 (Reuters) - Swiss drugmaker Novartis

reported first-quarter core operating profit below market

expectations on Tuesday, as generic competition for its

top-selling heart drug Entresto weighed on sales.

Quarterly group operating income, adjusted for special

items, declined 12% to $4.9 billion, below average analyst

expectations of about $5.1 billion cited by Visible Alpha.

Novartis is navigating what CEO Vas Narasimhan has

described as the drugmaker's largest patent expiry in the last

two decades, including for Entresto, which made up 14% of its

total net sales last year.

Entresto saw first-quarter sales drop 42% after its U.S.

patents expired and competing generics were launched. Entresto

faces patent expiries in Europe starting November.

Blood disorder drug Promacta and leukemia treatment

Tasigna also face competition from generics, increasing the

pressure on Novartis to deliver sales growth from newer drugs.

The Swiss group has said it expects its sales to decline by

$4 billion this year due to competition from generics for

Entresto and the other two drugs.

The Basel-based company also confirmed its full-year

forecast of a low single-digit percentage core operating income

drop, excluding currency swings.