X0202 4 2006-04-07 0 0001024520 WORLD HEART CORP WHRT 0001044321 MARXE AUSTIN W & GREENHOUSE DAVID M C/O SPECIAL SITUATIONS FUNDS 527 MADISON AVENUE, SUITE 2600 NEW YORK NY 10022 0 0 1 0 Common Stock 2006-04-07 4 P 0 78410 0.9993 A 12831747 I By Limited Partnerships Common Stock 2006-04-10 4 P 0 14721 0.9765 A 12846468 I By Limited Partnerships Common Stock 2006-04-11 4 P 0 15000 1.0098 A 12861468 I By Limited Partnerships This is a joint filing by Austin W. Marxe (Marxe) and David M. Greenhouse (Greenhouse). They share voting and investment control over all securities owned by Special Situations Fund III QP, L.P (SSFQP), Special Situations Cayman Fund, L.P. (Cayman), Special Situations Private Equity Fund, LP (PE), respectively. 6,614,001 shares of Common Stock and 6,117,036 Wts to purchase 873,861 owned by SSFQP, 2,169,103 shares of Common Stock and 2,217,742 Wts to purchase 316,820 Common Stock are owned by Cayman, 2,542,060 shares of common stock and 2,419,355 Wts to purchase 345,622 shares of common stock are owned by PE. The interest of Marxe and Greenhouse in the shares of Common Stock and Warrants owned by SSFQP, Cayman and PE is limited to the extent of his pecuniary interest. Austin W. Marxe 2006-04-12 David M. Greenhouse 2006-04-12