St. Jude Medical Begins Enrollment in the ASSERT Clinical Study to Evaluate the Relationship Between Atrial High Rate Episodes and Stroke.

ST. PAUL, Minn. -- St. Jude Medical, Inc. (NYSE:STJ) announced today enrollment of the first patients in the ASSERT (ASymptomatic AF and Stroke Evaluation in Pacemaker Patients and the AF Reduction Atrial Pacing Trial) clinical study. The study will follow 2,500 patients for 3 1/2 years to determine if pacemaker-detected AHRE (Atrial High Rate Events) predict an increased risk of stroke in elderly hypertensive patients without previous atrial fibrillation (AF). ASSERT also examines the efficacy of St. Jude Medical's AF Suppression(TM) algorithm in helping these patients avoid symptomatic AF.

"We begin the ASSERT study knowing that pacemaker patients commonly experience atrial high rate episodes, but the clinical significance remains largely unknown," said Stuart J. Connolly, M.D., Professor of Medicine, McMaster University, Hamilton, Ontario, Canada, one of the study's principal investigators. "We also hope to discover whether AF suppression technology prevents or reduces symptomatic AF episodes, along with reducing the burden of AF."

Sinan Gursoy, M.D., enrolled the first U.S. patient in the ASSERT study at Naples Community Hospital in Naples, Florida, and Seong-Wook Han, M.D., enrolled the first Asian patient at the Keimyung University Dongsan Medical Center in Daegu, Korea.

The ASSERT study, which is being conducted at 125 international clinical centers and coordinated by the Population Health Institute at McMaster University, is designed as a randomized, single-blinded study of elderly hypertensive patients with a first pacemaker for sinus or AV nodal disease. Patients enrolled in the study must be over 65 years old, have a history of hypertension requiring drug therapy, and be recently implanted with a St. Jude Medical Identity(R) ADx DR pacemaker with the AF Suppression(TM) algorithm.

Dr. Connolly and Dr. Stefan H. Hohnloser, Professor of Medicine at J.W. Goethe University in Frankfurt, Germany, are the principal investigators of this study, which is sponsored by St. Jude Medical.

"The state-of-the-art diagnostics in the Identity ADx pacemaker detect and track episodes of atrial tachycardia and atrial fibrillation, generating six-month trend graphs to help physicians better manage atrial high rate events," said Eric S. Fain, M.D., Senior Vice President of Development and Clinical/Regulatory Affairs for St. Jude Medical's Cardiac Rhythm Management Division. "When combined with the AF Suppression algorithm, we're optimistic that this approach may help optimize care of elderly hypertensive patients who have a standard bradycardia pacing indication."

St. Jude Medical's AF Suppression(TM) technology is the world's only algorithm clinically proven to suppress atrial fibrillation. It offers a device-based approach to continuously monitor the heart's intrinsic atrial activity and stimulate the atrium slightly above the patient's rhythm (overdrive stimulation), for the purpose of suppressing the onset of paroxysmal and persistent AF.

The AF Suppression(TM) algorithm provides atrial stimulation at well-tolerated, patient-tailored rates, whether the patient is active or at rest. Many previous atrial overdrive methods were based on fixed overdrive pacing, which can be uncomfortable for patients while relaxing or sleeping. In addition, fixed overdrive pacing usually can't result in the high percentage of atrial pacing that's possible with AF Suppression(TM) technology.

Atrial fibrillation, the most common chronic arrhythmia, affects 6 million people worldwide. It is a common risk factor for - and cause of - stroke. In the United States, AF presents an immense health care and financial burden, affecting over 2 million people with annual medical expenditures estimated at $6 billion dollars. The prevalence of AF increases as the population ages. Characterized by rapid, uncoordinated and uncontrolled contractions of the atria (upper chambers of the heart), AF prevents the heart from efficiently pumping blood and diminishes quality of life.

Any statements made regarding St. Jude Medical's anticipated future product launches, regulatory approvals, revenues, earnings, market shares, and potential clinical successes are forward-looking statements which are subject to risks and uncertainties, such as those described in the Financial Section of the Company's Annual Report to Shareholders for the fiscal year ended December 31, 2003 (see pages 11-16). Actual results may differ materially from anticipated results.

St. Jude Medical, Inc. (www.sjm.com) is dedicated to the design, manufacture and distribution of innovative medical devices of the highest quality, offering physicians, patients and payers unmatched clinical performance and demonstrated economic value.