Aetna Inc.'s second-quarter net income tumbled almost 15 percent compared with last year, when the health insurer caught a big break from lower-than-expected leftover claims. But the latest results still beat analyst expectations, and Aetna raised its 2012 earnings forecast. In the second quarter, Aetna’s net income fell to $457.6 million, or $1.32 per share. That’s down from $536.7 million, or $1.39 per share, a year ago. Adjusted earnings, which exclude one-time items, were $1.31 per share. That topped the $1.25 per share that analysts expected. Revenue rose 6 percent to $8.84 billion, also above analyst expectations of $8.75 billion.