Some other ARBs and ACE inhibitors may
work less effectively or not at all (some ARBs I know to be good - besides
telmisartan - are valsartan, irbesartan, candesartan. Most of them are good EXCEPT for losartan, which is a surmountable antagonist and, theoretically, would lose its effect over time).
Next fact: you need to take a high dose.