Write Custom Header Title using Export

I would like to export a matrix of doubles with a comma as the delimiter. If the matrix is called numMat I have been using the following command.

export(dataset(numMat),'file','test.csv','Delimeter',',');

However, this produces a file whose first row is . . .

numMat_1,numMat_2,numMat_3,...

I want to be able to change the first row so that it more meaningfully describes each column.