St. Jude Medical initiates study to evaluate ST monitoring technology


St. Jude Medical has enrolled the first patient in its Analyze ST clinical trial to evaluate the effectiveness of an ST segment monitoring feature in the Fortify ST implantable cardioverter defibrillator (ICD) to detect acute coronary events.

Scott Allison and Paul B Tabereaux of Heart Center, Huntsville Hospital, Alabama, USA, implanted the first two patients in the trial. Allison commented, “When a patient is experiencing a heart attack, every minute counts. For every 30 minutes that treatment is delayed, mortality increases by 7.5. Because symptoms can be vague, and approximately one-third of patients do not even have typical chest symptoms, the average time it takes for a patient to seek treatment has remained at almost 3 hours over the last decade. We hope the device being studied in the Analyze ST trial can help provide physicians with more information about coronary events that will allow us to intervene and provide treatment earlier.”

The ST segment is a section of an electrocardiogram (ECG) that depicts electrical changes between heartbeats. Changes in ST segments have long been studied in clinical settings using external devices as indicators for cardiac ischaemia. However, due to several limitations, it has not been practical to study them on a continual basis. A method to monitor the ST segment without such limitations could provide important insights into the overall clinical assessment of patients at risk for coronary events. Monitoring for ST changes within the heart of an ambulatory patient may provide unique insight into the presence and severity of changes of the ST segment and occurrence of ischaemia in patients with coronary artery disease.

The Analyze ST trial (ST monitoring to detect acute coronary syndrome events in ICD patients) is a prospective, non-randomised, multicentre, pivotal IDE investigation of up to 5,228 patients at approximately 200 medical centres. The sensitivity of the feature for detecting acute coronary syndrome events will be the primary efficacy endpoint. The primary safety endpoint will be assessed by reporting the percentage of patients who experience a false positive detection.

“We know that ST segment changes can help us to identify coronary artery disease events, so the continuous, internal monitoring that is possible with this technology could provide physicians with an early warning signal that a patient is experiencing an ischaemic event,” said Mark Carlson, chief medical officer and senior vice president of research and clinical affairs for the St. Jude Medical Cardiac Rhythm Management Division. “Since many patients do not experience symptoms during a heart attack, this technology has the potential to improve the diagnosis and treatment of cardiac ischaemia.”

The ST monitoring feature is CE marked and has been used in St. Jude Medical ICDs since December 2008.

How does it work?

During ST segment shifts, the ICD records high-resolution electrograms that can then be transmitted, along with additional information, for download into the Merlin Patient Care System in the clinic, or to the Patient Care Network from the patient’s home via a Merlin@home transmitter. During the course of the study, the device’s patient alert feature will also be turned on, which would notify the patient via a vibratory alert when an ST segment change occurs.

Based on the Fortify platform, the Fortify ST ICD features advanced battery technology and circuitry that allow for a smaller device, the highest energy output delivery (40J) of any ICD, as well as rapid charge times, all while increasing device longevity. The devices’ narrow shape, along with their small footprint, allow physicians to implant them using a smaller incision, leading to less time spent closing the incision and a reduced scar for the patient.