Add one more conductor to the national sick list, and an important Pittsburgh premiere to the obituaries page.

Conductor Robert Spano has canceled his Pittsburgh Symphony Orchestra concerts this weekend due to bronchitis. Concertmaster Andres Cardenes will lead the PSO in a revised program.

Spano joins a who's who of big-name conductors who have canceled for various reasons this month: James Levine, Kurt Masur and Christoph von Dohnanyi.

"His doctors told him to stop working," said Robert Moir, PSO vice president for artistic planning.

Spano's cancellation, regrettable as it is for those looking forward to the American maestro's first appearance here in a decade, has further consequences. Lars Vogt still will perform Mozart's Piano Concerto No. 23, but John Adams' "Naive and Sentimental Music" and a Sibelius work are gone.

"Only four people have ever conducted 'Naive and Sentimental Music,'" said Moir of the piece that premiered in 1999. Those four -- Alan Gilbert, David Robertson, Esa-Pekka Salonen and David Zinman -- were unavailable.

"We had to give up the program," said Moir, who found out late Sunday about Spano. "It is a 47-minute piece that is profoundly complex. There is no way that someone who had not prepared the piece could do it in such short notice. We felt if we couldn't get someone to do the piece who had done this before, we shouldn't do it."

Moir did extend an offer to Adams himself, who has led the PSO before.

"He said he would love to do it, so I said we could reschedule it," said Moir, who added that it may be some time until schedules are in sync.

Even with the decision to alter the program, the PSO was in a bind. Other fill-in possibilities were falling through and both of its staff conductors -- Daniel Meyer and Lawrence Loh -- also were unavailable. That left the duty to Cardenes.

For two years now, Cardenes has acted as the PSO's version of departed Steelers wide receiver Antwaan Randle El. For four weeks out of the year, Cardenes has the role of cover conductor, the emergency go-to guy in situations like this. In September 2004, he took over when Pinchas Zukerman was double-booked for a concert.

He has only recently incorporated conducting into his professional life, but Cardenes has led the Pittsburgh Symphony chamber orchestra regularly for several years and has outside guest conducting experience.

The new program will be the Mozart concerto, Debussy's "Petite Suite," and Dvorak's Symphony No. 7.