You could use LinqToExcel to read the first row, and it should be faster because it doesn't have to load the whole file. However, LinqToExcel uses OLEDB to read the file instead of the Open XML SDK.
var excel = new ExcelQueryFactory("excelFileName");
var firstRow = (from c in excel.Worksheet()
select c).First();
Checkout the rest of the documentation for LinqToExcel.