These days there are a plethora of treatment options for abnormal heart rhythm patients – from antiarrhythmic drugs to pacemakers and implantable cardiac defibrillators (ICDs). But before the problem can be treated, the doc will most likely want to confirm the diagnosis, often with a physical examination and an electrocardiogram (ECG) evaluation through a Holter monitor.

Then there are those difficult-to-diagnose cases in which standard monitoring tests are not enough and an implantable cardiac monitor (ICM) is deemed necessary to evaluate the heart rhythm signals over a longer period of time. For those cases, St. Jude Medical (St. Paul, Minnesota) has developed an ICM the size of a computer thumb drive designed to provide more accurate sensing of the heart signals.

St. Jude said the FDA recently cleared its SJM Confirm ICM, which it says will help physicians diagnose and document difficult-to-detect rhythm disorders in patients who may suffer from unexplained symptoms, including fainting, palpitations and shortness of breath. At 6.5 cc the Confirm is the smallest ICM on the market, according to the company. The device is implanted just under the skin in the upper chest region during an outpatient procedure under local anesthesia.

"It is the smallest cardiac monitor available, it provides real time data and some devices that are out there do not do that," Kathleen Janasz, a St. Jude spokeswoman, told Medical Device Daily.

Janasz also said it was important that the Confirm ICM is approved for syncope (or, fainting), which is "one of the most difficult diagnoses to make."

According to St. Jude, syncope is responsible for about 3% of all emergency room visits and up to 6% of all hospitalizations. About 1 million people in the U.S. suffer from syncope, and about half of all cases of unexplained syncope go undiagnosed, St. Jude said, even after a physical examination and ECG evaluation.

"The SJM Confirm ICM was developed in response to physicians' need for more information about heart rhythm abnormalities, particularly in patients who are most challenging to diagnose," said Eric Fain, MD, president of St. Jude's cardiac rhythm management division. "This implantable monitor enables patients to record data that coincide with their symptoms and then send that data to their physicians remotely for diagnosis and determination of the best course of treatment for their arrhythmias."

St. Jude joins at least two other Minnesota companies in this sector, including Transoma (also St. Paul) and Medtronic (Minneapolis).

Transoma rolled out its Sleuth implantable monitoring system last year, which is designed to provide continuous monitoring for diagnosis of syncope. The Sleuth, a thin device about the size of a 50-cent piece is placed under the skin near the shoulder. The device is designed to continuously gather ECG data, and then automatically and regularly forward it to a monitoring center operated by Mednet Healthcare Technologies where cardiac technicians review the information and send reports of relevant cardiac event data to the doctor (Medical Device Daily, Oct. 31, 2007).

Medtronic received Japanese regulatory approval for its Reveal DX Insertable Cardiac Monitor in July, a device about the size of a memory stick inserted that is also inserted just under the skin of the chest area to monitor patients for up to three years. Reveal is also available in the U.S., Western Europe, and Canada. Although St. Jude's ICM is smaller, Medtronic's device is just slightly larger at 8 cc.

With the SJM Confirm ICM, patients are able to remotely send data to their doctor when they experience symptoms, St. Jude said. The device features a St. Jude sensing algorithm designed to enhance signal detection, thus enabling physicians to program the device to be more sensitive to small and wide-ranging signals. Electrodes on the monitor sense cardiac activity and a continuous loop recorder stores information about the heart's activity. The electrodes are positioned on opposite sides of the device; this design is intended to provide better contact with the subcutaneous tissue for more accurate sensing of heart signals, the company said.

"The better signal detection you've got the better information a physician has, the more reliable that information is," Janasz said.

The Confirm is the first implantable monitor to be built on a unified platform, which has enabled St. Jude to more quickly introduce devices with new features and diagnostics (as they become available) because the basic platform for all of the devices is the same. The St. Jude "Unity" device platform was introduced in September 2007 with the launch of the company's Promote RF CRT-D and Current RF ICD devices. Due to its uniform software interfaces and expanded features, the new platform gives physicians more choices during device programming and patient follow-up, St. Jude noted.

The Confirm ICM also features: programmable event triggers, which enable physicians to program the device to automatically capture and record up to 60 seconds before and after a cardiac event; three year device longevity; and compatibility with St. Jude's Merlin patient care system, a powerful, portable computer designed to help doctors access and analyze diagnostic information and print data reports.

The Confirm ICM will be launched in October, St. Jude said.