The California HealthCare Foundation (CHCF) has invested $1.5 million in iRhythm Technologies, maker of Zio Patch, an FDA-cleared ambulatory cardiac rhythm monitor. The Oakland, Calif.-based foundation also says it will sponsor studies of the technology at two safety-net health systems in the state.

Zio Patch differs from many other wearable monitors in that it does not have built-in wireless connectivity to a base station, smartphone or central server. Instead, the single-use product stores up to 14 days of data locally. After the monitoring period, users mail in the Zio Patch for analysis.

The trial will help clinicians at public hospitals, outpatient facilities and rural clinics detect and treat heart arrhythmia in patients who might not otherwise get the necessary care, according to CHCF and San Francisco-based iRhythm.

"iRhythm's Zio Patch technology has the potential to increase access to timely diagnosis and care for patients in both rural and urban environments," Margaret Laws, manager of the CHCF Health Innovation Fund, which is making the actual investment, says in a statement released just before Thanksgiving. "The simplicity of their approach to ambulatory cardiac monitoring minimizes logistical difficulties, promotes increased patient compliance and streamlines the process for patients and clinicians, making this a solution that can bring great value to underserved Californians," says Laws, who also directs the foundation's Innovations for the Underserved program.

"The Zio Patch also has the potential to reduce the cost of cardiac rhythm testing by reducing the number of times monitoring must be done before a diagnosis is obtained, which could result in overall reduction of costs to the healthcare system," Laws adds in an iRhythm press release.

The CHCF investment is small compared to earlier venture capital iRhythm secured from other investors. Notably, medical device manufacturer St. Jude Medical led a $10 million round of financing in 2010, along with Mohr Davidow Ventures and Synergy Life Science Partners. Last year, Kaiser Permanente Ventures offered up $7 million and New Leaf Venture Partners provided $15 million. All told, iRhythm has raised about $52 million in private equity.

Zio Patch received 510(k) regulatory clearance from the Food and Drug Administration in July, though it has been on the market since 2011. More than 85,000 patients have used the device, according to iRhythm.