BROOMFIELD - Arca Biopharma Inc. will use a heart monitor made by Medtronic Inc. in a clinical trial for Arca's heart drug Gencaro.

The trial will compare Gencaro to controlled and extended release metoprolol for prevention of atrial fibrillation in patients with heart failure and reduced left ventricular ejection faction. The form of metoprolol

Under the initial clinical study, approximately 200 patients will be tested, according to Broomfield-based Arca (Nasdaq: ABIO). Depending on the results of an interim analysis, the study would be expanded to include an estimated 420 additional patients.

Each patient will have heart rhythm monitoring via a Medtronic device. Medtronic (NYSE: MDT) will support the implantation and use of the Medtronic monitoring devices and manage the atrial fibrillation data collection and analysis.

"We are excited about our collaboration with Medtronic," said Michael Bristow, Arca's president and chief executive. "We believe that the use of implanted, continuous monitoring devices that allow for the more precise measurement of atrial fibrillation represents the next generation of diagnosis and treatment options for patients at risk for this disease."

Medtronic is based in Minneapolis and has operations in Louisville.

Earlier this year Arca Biopharma said it had "substantial doubt" about its ability to continue operations beyond September, according to documents filed with the Securities and Exchange Commission.

The publicly traded biotechnology lost $4.3 million in 2012 following a loss of $5.4 million in 2011, according to its annual report.

Officials said in the SEC documents they hope to continue development of Gencaro by pursuing an underwritten public offering to fund its general and administrative costs, as well as clinical trials for the drug.

Arca said it would seek partnering and licensing opportunities.

"If we are delayed in obtaining funding or are unable to complete a strategic transaction, we may discontinue our development activities on Gencaro or discontinue our operations," Arca said in the documents.

Arca has been in danger of being delisted from the Nasdaq stock exchange on several occasions because its stock price has fallen below $1 per share.

Arca completed a reverse stock split to raise its per-share trading price and regain compliance with Nasdaq stock market rules on March 4. As a result of the reverse split, every six shares of issued and outstanding common stock were combined into one.