Can you not simply use the first row of the repeater:
<?php
$rows = get_field('repeater_field_name' ); // get all the rows
$first_row = $rows[0]; // get the first row
$first_row_image = $first_row['sub_field_name' ]; // get the sub field value
// Note
// $first_row_image = 123 (image ID)
$image = wp_get_attachment_image_src( $first_row_image, 'full' );
// url = $image[0];
// width = $image[1];
// height = $image[2];
?>
<img src="<?php echo $image[0]; ?>" />
Taken from here: Repeater Documentation
