CDU Contributing Editor

ORLANDO, Florida One of the real buzzes at November's annual scientific sessions of the American Heart Association (AHA; Dallas, Texas) was the continuing clinical validation of the role of public access defibrillation in reducing mortality. Clinical studies showing the effectiveness of automated external defibrillators (AEDs) presented at the AHA conference were excellent news for virtually every major defibrillator company.

It means that the lowest-cost, automatic defibrillators will continue selling like hotcakes. With literally hundreds of thousands of locations still to be supplied, the end of the heated sales cycle for companies making AEDs seems nowhere in sight. With the dispute about which biphasic therapy is preferable still unresolved, that means all vendors Cardiac Science (Irvine, California), Medtronic PhysioControl (Redmond, Washington), Philips Medical/ Heartstream (Seattle, Washington), Zoll Medical (Chelmsford, Massachusetts), Welch Allyn/MRL (Buffalo Grove, Illinois) and others will proceed full speed ahead in the drive for market share.

The demand for such devices will be fueled further by research reported at AHA showing that early use by bystanders of AEDs can double survival for patients with heart attacks and, when combined with mechanical CPR, survival may rise to between 30% and 40% an astounding increase, from four to eight times better than currently experienced in most U.S. cities. It underscores further the importance of the combination of mechanical and electrical support of patients in cardiac arrests.

Laurie Morrison, MD, of Sunnybrook Hospital and Women's College Health Sciences Center (Toronto, Ontario), reported on studies of sudden cardiac arrest, a condition that strikes a quarter of a million Americans annually and normally results in less than 5% survival. Over 21 months, AEDs made available at 24 sites in the U.S. and Canada were used by 19,762 volunteer rescuers. Twice as many persons who experienced an arrest survived to hospital discharge in the AED group vs. those who only had the benefit of conventional emergency care (cardiopulmonary resuscitation, or CPR). These were patients who arrested in shopping centers, office buildings, sports arenas and some residential building complexes.

The role of the newer, smaller AEDs with biphasic waveforms was again validated in various studies reported at AHA. One study was the Canadian ORBIT study, in which 48 ambulance crews were trained in the early use of defibrillators. Among the 434 non-hospital patients treated for spontaneous sustained ventricular fibrillation or unstable ventricular tachycardia, there was no difference in success between older monophasic, high-energy defibs that have historically been used and newer, smaller, lighter, cheaper AEDs with biphasic waveforms. This shows that the newer, biphasic AEDs are at least as good as older technologies available, which usually come in bulkier packages.

Other studies suggest that cardiac damage and other complications are less with these newer AEDs than the units they are now displacing, particularly in reducing the development of cardiac arrhythmias after defibrillation. Zoll Medical is among those which hope that the upcoming ORBIT 2 study involving 700 Toronto, Ontario, patients, when combined with ORBIT, will be sufficient to demonstrate differences in efficacy of its lower-energy, rectilinear waveform therapy. So far, no individual study has done that. The PAD (Public Access Defibrillator) trial was insufficient by itself to answer the question.

A rough estimate of the market for public AEDs among EMS personnel can be obtained from the ORBIT trials. In Toronto, with 4.5M people, 2,500 arrests were expected per year. The city had 24 stations containing 48 ambulances, staffed by 900 paramedics. Each ambulance needed one AED. The response time was not stated, so more crews and vehicles might be needed for the same population in other cities given their specific geographic complexity and traffic situations.

In addition to showing its popular M-series CCT on the McCormick Place exhibit floor, Zoll also was showing its new M-Series AED and M-Series with optional noninvasive blood pressure. The company highlighted a paper presented by Morrison that suggested Zoll's rectilinear protocol was superior to monophasic waveforms.

Philips was showing its HeartStart MRx high-acuity monitor defibrillator intended for either BLS or ALS applications. At 13.2 pounds, however, it may be a bit big and heavy to also fill first-responder applications.

Changes in defibrillation were not limited to AEDs used by first responders. The AHA meeting was the venue for the LifeVest patient-worn defibrillator, a novel arrangement of electrodes, belt battery packs and a small, biphasic shock delivery unit that allowed patients at high risk of sudden death to carry their potentially life-saving defibrillator with them while they are awaiting receipt of an implantable cardioverter defibrillator (ICD). One such device was being shown in the Zoll booth, although the device is manufactured by LifeCor (Pittsburgh, Pennsylvania), which also had a booth at AHA. About 50% of LifeCor's customers are waiting for ICD implants, while another 20% are congestive heart failure patients, 8% of customers are post-myocardial infarction (MI) patients, 4% are post-CABG patients, 5% are patients on arrhythmic drug loading and 3% are cardiomyopathy patients. Most of these patients are transitory users of the device; however, there are new patients entering these categories each year, so on a rental basis, there is a constant flow on prospective new clients. The LifeVest device makes sense for high-risk populations because after an MI, about 95% of patients in the pre-hospital setting die within 10 minutes if not shocked or provided with good CPR.

MADIT II study opens up $3B market

There was good news on the implanted defibrillator (ICD) front as well. As noted by AHA President Augustus Grant, MD, of Duke University (Durham, North Carolina in his keynote speech, the market for ICDs based on criteria used in the MADIT II ICD study would be $3 billion, large enough to attract even more attention by current ICD manufacturers such as Guidant (Indianapolis, Indiana), Medtronic (Minneapolis, Minnesota), St. Jude Medical (St. Paul, Minnesota) and others. This is in addition to the $5 billion market for left ventricular assist devices to treat advanced heart failure. This implies that the realizable market for such devices will be limited by what the government is actually willing to expend for such therapies, making reimbursement for such therapies a highly political issue over the next decade.

In a study of exercise's relationship to ICD shocks, it was found that 23 ICD patients experienced 36 shocks during exercise that ranged from 3.5 METS (equivalent to walking) to around 7 METS (equivalent to playing tennis or basketball). In all cases the shock restored normal rhythms without serious injury. This suggests that patients with ICDs can participate in reasonable exercise activities.

ICDs also are being studied for prophylactic implant in some high-risk patients. In the DEFINITE study, lead investigator Alan Kadish, MD, of Northwestern University (Evanston, Illinois) reported a group of 458 patients, all with ejection fractions of <0.36. Of these, 229 received single-chamber ICDs in addition to drug therapy (ACE inhibitors, beta blockers, etc.). Of the 56 total deaths, 33 were in the control group and 23 were in the ICD group. At two years, mortality in the control group was 13.8% vs. 8.1% in the ICD group, showing that placement of ICDs in this patient population (non-ischemic cardiomyopathy with low ejection fractions) reduces all-cause mortality. Several other studies are finding improvements in survival of patients reaching hospitals after collapse on the order of 50% when AEDs are available and promptly used.

Elsewhere at AHA

Guidant showed its Insignia Ultra pacemaker, cleared for marketing by the FDA while the AHA meeting was ongoing. This is the company's most advanced pacemaker, offering automatic capture by evaluating every beat to see if the heart's ventricles have contracted in response to the trigger from the SA node. If not, the pacer issues a backup pulse to assure ventricular contraction. Pacing is an important therapy for heart failure patients, particularly the 30% to 50% of them whose four heart chambers do not work together due to cardiac tissue damage. The decreased output in such situations provides very little, if any, "cardiac reserve" for patients, who are easily fatigued, become short of breath and develop fluid retention. By helping to better coordinate the heart muscle that remains, cardiac output is enhanced. Pacing and implanted cardiac defibrillators have been shown to be very effective in extending life for heart-failure patients and reducing the incident of sudden cardiac death. Guidant also markets the Contak Renewal as part of its CRT-D family, which offers enhanced monitoring of heart rate variability and provides an Activity Log by capturing data from an integrated "motion sensor" to track trends in patient activity. This allows the patient's doctor to correlate pacer response to patient activity, providing new information about the heart's response to increased demand.

There is growing awareness among cardiologists (as there is among anesthesiologists) that sleep-disturbed breathing poses both a long-term risk and a risk during interventions, like anesthesia. As a co-morbidity with drug-resistant hypertension (80%), stroke (60%), CHF (50%), hypertension (45%) and coronary artery disease (30%), the market for CPAP and derivative airway ventilators is thriving. Moreover, SDB has been recently associated with elevated blood pressure (BP), which is an independent risk factor for heart attack. Therefore, treating SDB can reduce BP and reduce the risk of heart attack. This is good news for Respironics (Murrysville, Pennsylvania), Resmed (Poway, California), Tyco/Puritan Bennett (Pleasanton, California) and others who make various continuous positive airway pressure (CPAP) SDB has been found to require additional care during emergence from anesthesia, and at the AHA this year there were studies presented that SDB also is an independent risk factor for patients with coronary artery disease, leading to a poorer quality of life.

GE Medical Systems Information Technologies (Milwaukee, Wisconsin) used the AHA to show its new Centricity information system interfaces to its Mac-Lab and CardioLab products. This provides the connectivity for cath and ECG analysis data to flow into the Centricity repository from which queries and various reports can be generated to support data-driven clinical decisions. Products compatible with these new interfaces range from Mac-Lab 7000, CardioLab 7000 and ComboLab 7000 series products. This represents a major step forward as GE provides connectivity across a broad range of its own diverse product lines. Following the growing awareness that women have heart disease, most AHA studies and many vendors are jumping on the women's cardiac care bandwagon. GE Medical announced that it had modified its ECG analysis software to make it "gender aware." This appeared in a new version of the Mac 5000 electrocardiogram software, which GE claims is 14% more accurate than its older, non-gender-specific software versions.

GE competitor Philips Medical also was showing ECG analysis algorithms that not only are gender aware but also take patient age (neonatal, pediatric, adult) into account when analyzing ECGs. This was being shown on the company's new ECG analysis cart. Philips also was showing its Xcelera Cardiology Information System that it expanded to include data acquired in the cath lab, in echocardiology from ultrasound units, in nuclear medicine and during cardiac magnetic resonance studies. It provides the same type of data integration, queries and reporting as the GEMS system shown at AHA.

i-STAT (East Windsor, New Jersey) was showing some new test sets that complement its InRatio hand-held, point-of-care tester. One such test was for prothrombin time, a test required frequently by patients at home who are on blood thinning drugs. The notion of self-testing by patients at home and the subsequent reduction in office visits to physicians, who receive the data directly from patients, is yet another example of procedures that were previously done in the hospital or physicians' office setting now moving to the home care setting. CMS approved this for patients with mechanical valves last June, but is widely expected to extend reimbursement to other types of patients this year. Various Blue Cross and other third-party payers have followed the CMS lead and also offer reimbursement. The new i-STAT units cost $1,995 and the test kits are about $10 per test. CMS approves one home test per week presently. Other patients who could benefit from expanded use would include patients with deep vein thrombosis (DVTs) who are at risk for pulmonary embolism.

i-STAT also was showing its i-Stat 1 System and a new troponin I and ACT-Kalin tests for emergency departments. This should help EDs comply with AHA/American College of Cardiology (Betheseda, Maryland) guidelines to obtain cardiac markers with- in 30 minutes, which can otherwise be difficult particularly for patients that present on weekends and during night shifts. Having better and earlier diagnostic markers can perhaps reduce the 11,000 (of the total 1.1 million) patients who have MIs but, because the diagnosis is missed, they are discharged home, and subsequently die. This new device also includes bar code scanning to capture drug, patient and provider ID and annotate test time all efforts to reduce medical test reporting errors. This new hospital scanner costs around $6,000, according to company booth personnel and integrates with the Precision NET data networking system.

Rozinn (Glendale, New York) is known for its Holter recorders. At AHA, it was showing its new Cardio ID+ model, a 3-channel, solid-state unit that replaces older tape and loop technologies. The unit features real-time pacer detection and samples the patient's ECG at 180 samples per second. The real news from Rozinn, however, was what that it was not showing an updated version of this product that was to be introduced before year-end, which acquires 12-lead ECG at a sampling rate of 1,024 samples/second. This new version will use the newest 1-gigabyte memory card to hold all of the data acquired, which will open up a whole new market for high-resolution data capture and analysis. The company was discussing this product as a "work-in-progress," as the new unit is not yet FDA-cleared.

Finapres Medical Systems (Arnhem, the Netherlands) was showing an updated version of its Finometer and Portapres products. The new Finometer, which was introduced in October, is aimed at directly tracking pressure-related syncope (fainting), a condition hard to detect and diagnose without continuous BP monitoring. There are four types of syncope, and determining proper treatment is challenging without knowing which type is involved. The new monitor corrects for hydrostatics height of the sensor, eliminating the static pressure artifacts and distortions that have plagued earlier generations of this product. The newest unit claims to correctly measure BP even if the hand is in motion during the measurement and moving up or down related to heart position. The other new Finapres product, the Portapres, uses two mini-finder cuffs that alternate while a patient sleeps to measure pressure. This new, dual-sensor approach is apparently less disruptive to sleep, allowing patients being monitored to be less aware of the pressure measurements that are being taken as they sleep.

New Physiostat ECG Analysis products were shown by Data Sciences International (St. Paul, Minnesota). These miniature telemetry devices are intended for animal implant for drug and other studies, but a human version also is being shown for use with CHF patients to provide Internet data reporting and titration of drug therapy.