* Q1 adj EPS $0.12 vs. $0.09 last year

* Q1 rev $42.1 mln vs. est $43.2 million

* Shares fall 7 percent after the bell

BANGALORE, April 30 (Reuters) - Athenahealth Inc (ATHN.O: Quote, Profile, Research) reported first-quarter results below market estimates, sending its shares down 7 percent after the bell.

"It's probably the fact that revenue were a bit lighter in the quarter than people were expecting," Caris & Co analyst Leo Carpio said by phone, referring to the stock price decline.

For the quarter, the provider of Internet-based billing and other services to physicians earned $2.3 million, or 7 cents a share, compared with $1.8 million, or 5 cents a share, in the year-ago period.

Total revenue rose 41 percent to $42.1 million, missing analysts' expectations of $43.2 million.

Excluding stock-based compensation and other items, adjusted net income was 12 cents a share.

According to Reuters Estimates, the company earned 6 cents a share, excluding items but including stock-based compensation, missing analysts' consensus view of 9 cents.