Between the 17th century renovations and 1821 this side altar was dedicated to Saint Michael the Archangel and was under the patronage of the Picco family. From 1822 to 1872 it seems to have been dedicated to Saint Francis de Sales and been under the patronage of the noble Deabbate family, who inherited it from the previous patrons.
From 1872 to 1933 it was also dedicated to the Sacred Heart of Jesus and to Saint Teresa of Avila (already depicted in the altarpiece). Dedications to the Madonna of Mount Carmel and Saint Francis of Assisi were also added. But originally it was the 19th-century dedication of the altar to the bishop saint and Doctor of the Church, protector of writers and journalists, that prevailed.
A large arched altarpiece is displayed on the altar table, showing Saint Francis de Sales, Saint Teresa of Avila and angels. By an unknown artist, it was painted on canvas in the last two decades of the 17th century and partially retouched in the early 1820s. It seems the work was acquired around 1822 by the erudite count Vincenzo Deabbate (Patrizio d’Alba Pompeia natio di Cuneo, “from Alba Pompeia, born in Cuneo”) for this side altar.