Hello,
UPDATE: The createTableStyle method includes a lot of optiones to apply styles to tables, such as firstRowStyle to apply style only to the first row.
There's no option to format only the first row, but you can set some settings for each cell of the first row using WordFragments.
For complex tables we recommend you to use embedHtml, you can read some samples about tables on http://www.phpdocx.com/documentation/introduction/html-to-word-PHP. Using HTML you can customize the first row of tables.
Regards.