True, Malbec is grown in Napa Valley and Sonoma Valley, but it's usually blended a la Bordelaise as part of a Meritage concoction.
Most commonly, winemakers blend Merlot with other Bordeaux grapes such as Cabernet Sauvignon, Cabernet Franc, Petit Verdot, Malbec, and Carménère.
Although Malbec is missing, the remaining royalty of Cabernet Sauvignon, Cabernet Franc, Merlot, and Petit Verdot are all present and accounted for in this Bordeaux-style red wine.
The principal vines grown in the Medoc are the Cabernet-Sauvignon, which is the most important, the Gros Cabernet, the Merlot, the Carmenere, the Malbec, and the Verdot.
There are minor plantings of Malbec, Cabernet Franc, Petit Verdot, Grenache, and Syrah, as well, to add depth and balance to many of their varietals.