Moving toward validation, standards
Ultimately, cuffless BP monitors may require more than one validation protocol and standard, depending on their technology, how and where they will be used, and by whom.
And as Dr. Plante and colleagues write, “Importantly, validation should be performed in diverse and special populations, including pregnant women and individuals across a range of heart rates, skin tones, wrist sizes, common arrhythmias, and beta-blocker use.”
Organizations that might be expected to help move validation and standards forward have mostly remained silent. The American Medical Association’s US Blood Pressure Validated Device Listing website includes only cuffed devices, as does the website of the international scientific nonprofit STRIDE BP.
The European Society of Hypertension 2022 consensus statement on cuffless devices concluded that, until there is an internationally accepted accuracy standard and the devices have been tested in healthy people and those with suspected or diagnosed hypertension, “cuffless BP devices should not be used for the evaluation or management of hypertension in clinical practice.”
This month, ESH published recommendations for “specific, clinically meaningful, and pragmatic validation procedures for different types of intermittent cuffless devices” that will be presented at their upcoming annual meeting June 26.
Updated protocols from IEEE “are coming out soon,” according to Dr. Shimbo. The FDA says currently cleared devices won’t need to revalidate according to new standards unless the sponsor makes significant modifications in software algorithms, device hardware, or targeted patient populations.
Device makers take the initiative
In the face of conflicting reports on accuracy and lack of a robust standard, some device makers are publishing their own tests or encouraging validation by potential customers.
For example, institutions that are considering using the Biobeat cuffless blood pressure monitor watch “usually start with small pilots with our devices to do internal validation,” Lior Ben Shettrit, the company’s vice president of business development, said in an interview. “Only after they complete the internal validation are they willing to move forward to full implementation.”
Cardiologist Dean Nachman, MD, is leading validation studies of the Biobeat device at the Hadassah Ein Kerem Medical Center in Jerusalem. For the first validation, the team recruited 1,057 volunteers who did a single blood pressure measurement with the cuffless device and with a cuffed device.
“We found 96.3% agreement in identifying hypertension and an interclass correlation coefficient of 0.99 and 0.97 for systolic and diastolic measurements, respectively,” he said. “Then we took it to the next level and compared the device to ambulatory 24-hour blood pressure monitoring and found comparable measurements.”
The investigators are not done yet. “We need data from thousands of patients, with subgroups, to not have any concerns,” he says. “Right now, we are using the device as a general monitor – as an EKG plus heart rate plus oxygen saturation level monitor – and as a blood pressure monitor for 24-hour blood pressure monitoring.”
The developers of the Aktiia device, which is the one Dr. Topol tested, take a different perspective. “When somebody introduces a new technology that is disrupting something that has been in place for over 100 years, there will always be some grumblings, ruffling of feathers, people saying it’s not ready, it’s not ready, it’s not ready,” Aktiia’s chief medical officer Jay Shah, MD, noted.
“But a lot of those comments are coming from the isolation of an ivory tower,” he said.
Aktiia cofounder and chief technology officer Josep Solà said that “no device is probably as accurate as if you have an invasive catheter,” adding that “we engage patients to look at their blood pressure day by day. … If each individual measurement of each of those patient is slightly less accurate than a cuff, who cares? We have 40 measurements per day on each patient. The accuracy and precision of each of those is good.”
Researchers from the George Institute for Global Health recently compared the Aktiia device to conventional ambulatory monitoring in 41 patients and found that “it did not accurately track night-time BP decline and results suggested it was unable to track medication-induced BP changes.”
“In the context of 24/7 monitoring of hypertensive patients,” Mr. Solà said, “whatever you do, if it’s better than a sham device or a baseline model and you track the blood pressure changes, it’s a hundred times much better than doing nothing.”
Dr. Nachman and Dr. Plante reported no relevant financial relationships. Dr. Shimbo reported that he received funding from NIH and has consulted for Abbott Vascular, Edward Lifesciences, Medtronic, and Tryton Medical.
A version of this article first appeared on Medscape.com.