While heart disease remains one of the leading causes of death worldwide, the number of drugs in development to combat the illness has reduced in the last 20 years, a study found.

The study published Monday in JACC: Basic to Translational Science analyzed data from a vast commercial database of drug development activity focusing on all drugs intended to treat cardiovascular disorders that entered Phase 1 clinical trials from Jan. 1, 1990 to Dec. 31, 2012. The database carried information tracking the pipeline of pharmaceutical research and development projects.

About 347 drugs meant for treating cardiovascular disease entered Phase 1 clinical trials during this time frame. Most drugs were antihypertensive agents, lipid-lowering agents and anticoagulants. From 1990 to 1995, 16 percent of drugs that entered Phase 1 trials were meant to treat cardiovascular diseases. However, between 2005 and 2012 only 125 cardiovascular drugs of 2,366 drugs, or five percent, made it to the Phase 1 testing.

The number dipped further in 2012 when cardiovascular drugs accounted for only seven percent of Phase 3 testing indicating that the number of cardiovascular drugs entering clinical trials in all stages of development had fallen over time. On the other hand, the number of cancer drugs in development had increased in the same time frame.

“These findings shed light on several important shifts in cardiovascular research and development activity over the past two decades. Importantly, while the overall number of new investigational cardiovascular drugs has declined, we also found a relative growth in the number of drugs targeting novel biological pathways,” senior author of the study Aaron S. Kesselheim from Harvard Medical School said in a statement.

Nearly half of the cardiovascular drugs that entered Phase 3 testing targeted a new biological pathway, one for which the U.S. Food and Drug Administration (FDA) is yet to approve a therapeutic agent. The rate of new drugs entering Phase 3 trials increased from 27 percent in 1990-1991 to 57 percent in 2012.

Development of cardiovascular drugs was mostly sponsored by major pharmaceutical companies but the number of such drugs sponsored by small or medium-sized companies has grown over time.

“These findings are not entirely glass-half empty,” Douglas L. Mann , editor-in-chief of JACC: Basic to Translational Science, said. “ Part of the decline in new drugs is that there are less ‘me too’ drugs that are similar to those already available. The study also refutes the premise that cardiovascular drugs are often riskier to develop than drugs in other clinical categories.”