Long Table with Markdown Conditional Header

LongTable.tex

\begin{longtable}[]{@{\extracolsep{\fill}}lccl@{}}
\toprule
	Col1 & Col2 & Col3 & Col4\tabularnewline
\midrule

\ifdefined\MARKDOWN
	\endhead
\else
	\endfirsthead

	\multicolumn{4}{c}{{(Continued from previous page)}} \\
	\toprule
	Col1 & Col2 & Col3 & Col4\tabularnewline
	\midrule
	\endhead

	\midrule \multicolumn{4}{c}{{\tablename\ \thetable{} continued on next page\ldots}} \\
	\endfoot
	\endlastfoot
\fi

  & & & \\
\bottomrule
\caption{}
\label{tab:}
\end{longtable}