You can use the readcell function to readout the cell.
The following is an example, assuming you have merged cells A1 to D1 you can specify the range as,
M = readcell('Book1.xlsx','Range','A1:D1');
This will readout 4 cells with M(1) containing the required text
M = readcell('Book1.xlsx','Range','A1:A1');
This will readout the merged cells with M containing the required text
Kiran Felix Robert