NEW YORK (CNS) -- Toward the end of his first apostolic visit to the U.S. in many years, Ecumenical Patriarch Bartholomew of Constantinople was hospitalized Nov. 3 at Mount Sinai Hospital in the New York City to undergo stent placement.

He was released Nov. 5 and expected to return to Turkey Nov. 7 after completing the rest of his visit, which was extended by four days because of his hospital stay.

A news release from the Greek Orthodox Archdiocese of America announced Nov. 3 the patriarch had had a check-up at Mount Sinai that led to an angiogram, which determined the need for stent placement to open a clogged coronary artery.

The 81-year-old patriarch is the primary spiritual leader of the world's estimated 300 million Orthodox Christians, and he is celebrating the 30th anniversary of his election this year.

He arrived in Washington Oct. 23 to begin his visit and the next day, before a scheduled service at the Cathedral of St. Sophia, he was admitted to George Washington University Hospital where he stayed overnight on medical advice.

The patriarch "felt unwell due to the long flight and schedule of events upon arrival," the archdiocese said.

But upon his release Oct. 25, he began a rigorous itinerary that included meetings that day with President Joe Biden in the Oval Office at the White House and Secretary of State Antony Blinken at the State Department as well as a visit to the Turkish Embassy at the invitation of Turkish Ambassador to the U.S. Hasan Murat Mercan.

Later, the patriarch said in a statement that he and the president had "a warm and productive meeting" but that their discussion also involved a shared sense of urgency about the world's climate crisis.

"In the course of our conversation, we touched on many issues that pertain to the peace of the world and the hope for increased environmental justice on this single planet that we all share," the patriarch said.

"We note with appreciation the president’s commitment to environmental responsibility and his willingness to lead the way," he added. "We have supported these efforts for the entirety of our 30-year patriarchy, and we shall continue to do so."

Patriarch Bartholomew said he expressed to Biden "our concerns for global stability" and the role that "constructive and positive religious movements can bring" to such stability.

"Our efforts for promoting Christian unity and interfaith understanding and cooperation have but one principle -- dialogue. We consider dialogue as the most effective means to address any challenge of the present or the future," he added.

Later, he attended a dinner at Georgetown University hosted by John J. DeGioia, university president, and Cardinal Wilton D. Gregory of Washington.

As a dramatic backdrop to his visit, a new icon was on display at the chapel showing apostles and brothers St. Andrew and St. Peter embracing each other -- reflecting the fraternal ties between the Orthodox and Catholic churches and the friendship and shared work of the patriarch and Pope Francis.

Greeting the patriarch at the university's Copley Crypt Chapel, Cardinal Gregory said: "Your presence here today among us reaffirms our mutual commitment to dialogue and to the work of Christian unity."

The patriarch met with House Speaker Nancy Pelosi, D-Calif., on Capitol Hill Oct. 26, following a reception at the United Methodist Building hosted by the National Council of Churches.

His itinerary for the rest of the trip included a variety of events in Pittsburgh and at the University of Notre Dame in South Bend, Indiana, before he went to New York.

At Notre Dame Oct. 28, he received an honorary doctorate, presented by Holy Cross Father John I. Jenkins, Notre Dame's president, during an academic convocation held on campus at the Basilica of the Sacred Heart.

"Religion must function and serve in connection with -- and never in isolation from -- science," the patriarch said in an address on environmental stewardship he delivered during the convocation.

He congratulated Notre Dame for the steps it has taken to reduce the university's carbon footprint by half within the present decade. "Even the overarching theme of your scholastic year is focused on the global climate crisis," he said.

Like climate change, "the global crisis of the novel coronavirus has presented us with ultimate questions about life and death, sickness and suffering, as well as health care and justice," he said.

"Our response to COVID-19 is the very arena where all Christian believers -- and, indeed, all people of goodwill -- are called to be and struggle. Otherwise, the truth is that we are not living up to our vocation as preachers of Christ ... and disciples of our Lord," Patriarch Bartholomew said.

"Similarly, protecting the natural environment is neither a liberal nor a sentimental response," he continued. "It involves constant pain and forgiveness, unrelenting preference and priority for what we truly value, for what really matters. It is the spiritual and moral response, whereby we become a healing and transformative presence among our neighbors and on our planet."

He also emphasized "the ecumenical imperative of our response."

"We faith leaders are called humbly and patiently to cooperate with leaders in the scientific and academic worlds, as well as the corporate and political domains," he said. "This interconnectedness reminds us that the earth unites us beyond any doctrinal, social or cultural differences."

In New York, Patriarch Bartholomew received the Human Dignity Award from the American Jewish Committee Nov. 1.

The award was an exact facsimile leaf of chapter 1 of the Book of Genesis in the Kennicott Bible, an illuminated Hebrew Bible from medieval Spain.

Rabbi Noam Marans, AJC's director of interreligious and intergroup relations, presented the award.

It recognizes the patriarch's "singular care for humanity and the environment, exceptional commitment to interreligious coexistence and indispensable advancement of Orthodox-Jewish relations," he said.

On Nov. 2, the patriarch presided at the "thyranoixia," or "opening of doors," ceremony at St. Nicholas Greek Orthodox Church and National Shrine, which has been under construction for several years and is due to be completed next year.

The structure is being built on the site of the parish church that was destroyed on 9/11 during the terrorist attacks on the World Trade Center. St. Nicholas Church was among many buildings destroyed or damaged by debris from the collapse of the trade center's twin towers.

The new church and shrine also will honor those who lost their lives on 9/11.

That evening Patriarch Bartholomew marked the 30th anniversary of his election with a celebration and dinner hosted by Archbishop Elpidophoros of America and the Friends of St. Nicholas.

Patriarch Bartholomew told dinner attendees the role of the ecumenical patriarch "has been, and continues to be, the modulating influence that hold the rudder of the ship of the church firmly, as she navigates the waters of modernity and secular change."

"Beloved children in the Lord: The church is greater than anything we can imagine. Our holy God, worshipped in Trinity, calls all people to communion and to the life in Christ," he said.

"We were not placed here to rule anyone other than ourselves. But we are all called to serve everyone. And to serve them humbly, righteously, and always with mercy and compassion," the patriarch added.