  Context: The influence of stellar multiplicity on planet formation is not yet
well determined. Most planets are found using indirect detection methods via
the small radial velocity or photometric variations of the primary star. These
indirect detection methods are not sensitive to wide stellar companions.
High-resolution imaging is thus needed to identify potential (sub)stellar
companions to these stars. Aims: In this study we aim to determine the
(sub)stellar multiplicity status of exoplanet host stars, that were not
previously investigated for stellar multiplicity in the literature. For systems
with non-detections we provide detailed detection limits to make them
accessible for further statistical analysis. Methods: For this purpose we have
employed previously unpublished high-resolution imaging data taken with
VLT/NACO in a wide variety of different scientific programs and publicly
accessible in the ESO archive. We used astrometric and theoretical population
synthesis to determine whether detected companion candidates are likely to be
bound or are merely chance-projected background objects. Results: We provide
detailed detection limits for 39 systems and investigate 29 previously unknown
companion candidates around five systems. In addition, we show for the first
time that the previously known companion candidate around HD 204313 is likely a
background object. By comparison with secondary epochs of 2MASS data we show
that the companion candidates around GJ176 and HD 40307, as well as two of the
sources around HD 85390, are likely background objects. For HD 113538 and HD
190984, as well as multiple further companion candidates around HD 85390,
further observational data is required to test common proper motion of the
companion candidates.
