Is minoxidil safe to use long-term?

I am 24 y.o. with receding hairline. Is minox safe to use long term? I have read a study where 6 months of topical minox use significantly increased left ventricular mass compared to placebo. I have also read studies showing that oral minox has known effects of left ventricular hypertrophy. Perhaps topical minox could result in more systemic absorption than assumed and result in ventricular hypertrophy. Is it safe for me to start using minox or could this result in heart failure when I'm older?