A spokesman for the Martha’s Vineyard Hospital confirmed yesterday that Dr. Timothy Tsai is no longer director of the hospital emergency room, although the hospital could not provide further details about the circumstances that led to his abrupt departure this week.

“Dr. Tsai is on leave from his position as director of emergency medical services,” said hospital spokesman Rachel Vanderhoop. “That is the only statement we are making right now,” she added.

Hospital president and chief executive officer Timothy Walsh was unavailable for comment.

Reached at his business office in Oak Bluffs yesterday, hospital board chairman Timothy Sweet also declined to comment. “It is a personnel issue and I should not be commenting on it,” Mr. Sweet said, adding: “I do know that Dr. Tsai has been a respected and valued member of the medical staff for a number of years.”

Ms. Vanderhoop denied reports that Dr. Tsai had been escorted from the hospital by security workers.

“That’s not true,” she said.

She said Dr. Jeffrey Zack, an emergency room physician, has assumed duties as director of emergency services.

Dr. Tsai began working at the hospital in January 2003, succeeding Dr. Alan Hirshberg. During Dr. Tsai’s tenure the hospital emergency room has been cited for excellence in delivery of care through patient satisfaction surveys.

The hospital emergency department was granted the Press Ganey Summit Award in 2007 and 2008, “reserved for clients that achieve and maintain the extraordinary,” a hospital press release said. The award is based on follow-up surveys among patients after they have received care at the hospital. Recipients must have ranked in the 95th percentile — the top five per cent in the nation — or above in the Press Ganey database for each reporting period for a minimum of three consecutive years.

Dr. Tsai’s clinical background includes a degree from St. Louis University School of Medicine, internship at Albert Einstein College of Medicine and residency at the Jacobi Medical Center. He is board certified in emergency medicine.

He is known for being community-minded, openly sharing emergency room statistics as they relate to public health trends, including for mental illness and depression, which have been documented at high rates on the Island. In 2005 he led a panel discussion on mental health titled Stress, Alcohol, Pills and People, using statistics from the emergency room to paint a stark picture of increasing numbers of people struggling with depression, alcohol and drug dependency.

A native of Worcester, Dr. Zack received his undergraduate degree from the College of the Holy Cross and his medical degree from the University of Massachusetts Medical School in 1998. He completed his residency at Brown University in emergency medicine in 2002; he is board certified in emergency medicine. In addition, he holds a degree in tropical medicine and travelers’ health and has practiced emergency medicine in Africa, Central and South America, Southeast Asia, and Micronesia.

He began work in the Vineyard hospital emergency room in 2002. “We are the primary care for a lot of the Island,” he told the Gazette in an interview in 2004.

With a partner he recently launched Lifeguard Medical Group on the Vineyard, a medical concierge service aimed at seasonal residents that offers personal medical services at home for people with an ability to pay for such services. Its Web site notes that full services are available from Memorial Day weekend to Columbus Day.

Dr. Tsai’s sudden departure comes not only as the busy summer season approaches, but at a time of critical transition at the hospital as final preparations are under way for a move into the new $48 million facility that was recently completed but is not yet occupied. The larger emergency room is a central feature of the new building.