Actress Minka Kelly and a host of other celebrities lit up the catwalk in various shades of red last week at New York City's Hammerstein Ballroom for a common cause: to raise awareness for women’s heart health.

Minka Kelly on the runway

Minka Kelly, who served as a Diet Coke Heart Truth ambassador for the second straight, wore a gown designed by Oscar de la Renta.

Kelly walked in The Heart Truth Red Dress Collection show during Mercedes-Benz Fashion Week as Diet Coke’s celebrity ambassador for the second consecutive year, wearing a flowing chiffon gown designed by Oscar de la Renta. Losing her mom four years ago to cancer opened the Friday Night Lights star's eyes to the importance of a healthy lifestyle.

“Heart disease is the number-one killer of women in America, so I was really inspired to help build awareness and encourage women to take care of their hearts,” she said in an interview hours before the show. “This opportunity was a no-brainer and a great chance to use whatever voice and visibility I can to help.”

Kelly called working with de la Renta’s team “a gift,” but insisted the appeal of the partnership extends well beyond fashion. “When I got involved, it wasn't about the dress … it was about the cause,” she told InStyle. “I would wear a potato sack down the runway if I had to."

Diet Coke continues to support The Heart Truth to raise awareness for women’s heart health programs and research by blending fashionable style and the power of expression. Social media-inspired packaging aims to amplify the organization's message and spark a digital dialogue about heart health – and why it’s never too early, or too late, to learn more.

Millions of Diet Coke packages are prominently featuring the hashtag #ShowYourHeart, which encourages fans to upload and share heart-inspired photos. Through February, every photo tagged on Twitter and Instagram with #ShowYourHeart will trigger a $1 donation from Diet Coke to the Foundation for the National Institutes of Health (up to $100,000) in support of women’s heart health research programs.

“We hope every time someone picks up a Diet Coke can and sees the striking brushstroke heart design, they’ll use the hashtag to join the social conversation supporting this important cause,” said Erik Jenkins, Diet Coke brand manager.

Five lucky fans who entered a photo-sharing contest last month won trips to the star-studded event in New York, where they graced the red carpet, enjoyed a behind-the-scenes look at the show, met Kelly and looked down from the balcony as the models prepared for the runway.

Shoes arranged in a heart shape

Julie Wax's winning Instagram photo.

Julie Wax, who runs the I Heart Heels fashion blog, appropriately snapped a pic of several of her shoes arranged in a heart shape on her closet floor. The 31-year-year old mom from Little Rock, Ark. said the night balanced style and substance.

“Much of the event focused on awareness,” she added. “It was encouraging to hear that the numbers are starting to get better, but that much more needs to be done.”

During the show, each model shared a personal story about how heart disease has affected them. One in particular stood out. Cindy Parsons, who after losing her mother to heart disease, lost 77 pounds and lowered her blood pressure and body mass index (BMI) through a community program supported by The Heart Truth. She was the first non-celebrity participant to walk the Red Dress runway in the show's 10-year history.

“The crowd went crazy for her,” said photo contest winner Hilary Jarman of Jacksonvile, Fla. “At that moment, I thought, ‘Wow, this is what it’s all about.’ I’m very appreciative of Diet Coke and The Heart Truth for reminding women like me that this is an issue all of us need to be aware of, and that we have to take care of ourselves.”

Visit Coca-Cola Unbottled to read Jarman’s account of her experience in New York.