FRANKFURT (Reuters) - Bayer on Tuesday struck a collaboration deal with U.S. biotech firm Cytokinetics ( CYTK ) to acquire certain rights in Japan to an experimental heart drug, as the German group strengthens its cardiovascular business with smaller deals.

Cytokinetics ( CYTK ) will receive 50 million euros ($53 million) upfront, plus up to 90 million euros contingent on certain development achievements, Bayer said in a statement.

Cytokinetics ( CYTK ) also stands to receive up to 490 million euros from Bayer, depending on certain sales milestones.

The deal covers certain uses of drug candidate aficamten in hypertrophic cardiomyopathy, an inherited condition that limits the heart's pumping function.

German diversified group Bayer, which is burdened by debt, weak agriculture markets and costly litigation, has faced investor calls to boost its drug development pipeline.

In March, Bayer acquired European commercialization rights for heart drug acoramidis for up to $310 million from a group of companies.

($1 = 0.9448 euros)