Accurate and Rapid Cardiac Testing Results Are Vital

Cardiac biomarker testing is essential for emergency departments (EDs) and physicians in identifying patients who present with signs and symptoms of heart attack or shortness of breath. Rapid diagnosis is important because the majority of ED patients who present with suspected symptoms of acute coronary syndromes are actually experiencing other problems. Thus, it’s vital to rule out acute myocardial infarction (AMI) and determine appropriate treatment and disposition.

When a patient presents in an ED with chest pain or shortness of breath, speed and accuracy of testing is essential. If a diagnosis is missed, a patient having a heart attack in the ED might be sent home. Cardiac misdiagnosis is the number one malpractice issue in the ED, and such other test methods as EKGs can often miss some heart attacks when used in isolation, says Brendan Leigh, product director, Inverness Medical, Princeton, NJ.

When time is of the essence, this type of cardiac testing is sometimes performed at the point of care in the ED. Otherwise, it’s done in the lab, where there’s still a significant amount of cardiac testing done, and vendors offer testing devices for both scenarios. Jim Dodds, marketing manager, Indianapolis-based Roche Diagnostics Corp’s Cardiac 200 and clinical chemical cardiac tests, says whether testing is performed at the point of care or in a lab depends on the required turnaround time of results.

The most frequently ordered test for AMI is cardiac troponin; serial testing may be performed to continue to look for changes in cardiac troponin levels. The creatine kinase MB (CK-MB) test is sometimes ordered by clinicians, with the myoglobin test used less often. Natriuretic peptide testing (NT-proBNP/BNP) is often ordered as an aid in the diagnosis of suspected congestive heart failure.

When fast results are necessary, Dodds says, labs are finding many ways to accelerate quick turnaround times. The American College of Cardiology and the American Heart Association have set standards for obtaining test results, usually 60 minutes or less from the time when a patient first presents to the ED. Even shorter times appear to offer even more positive outcomes, so if a lab can’t meet those turnaround times, ED testing or dedicated rapid analyzers may be used in the lab for even faster results. Roche’s automated equipment offers a 9-minute turnaround time for cardiac test results, Dodds says.

Analyzers for Cardiac Markers

In the lab, Roche’s cobas® 6000 features a series of analyzers to meet workload and test volume challenges, Dodds says. “This integrated system, with just a single sample, can be used to test for cardiac markers, magnesium levels, hCG, and a full metabolic panel. Another solution, the cobas® 4000, performs clinical chemistry and immunoassay testing for laboratories. Like the cobas 6000, this virtually integrated system uses a single sample tube type to obtain results for cardiac and other commonly ordered tests for each patient.”

In addition, the Roche Cardiac 200 is used for troponin I, NT-proBNP, CK-MB, and myoglobin testing. Roche’s automated D-dimer test aids in the exclusion of deep vein thrombosis and pulmonary embolism. Other tests for cardiac risk markers include those for cholesterol, HDL, LDL, and sometimes high sensitive c-reactive proteins, Dodds says.

According to Dodds, the biggest challenge facing cardiac testing is that more sensitive troponin assays are needed. “The belief is that with a more sensitive assay, the better the potential for a clinician to diagnose MI earlier. Faster turnaround times mean physicians may be able to intervene quicker for better outcomes.”

Roche cardiac testing systems are used in both hospital and nonhospital labs and are moderately complex, so labs need CLIA licensing for such systems. (By contrast, such tests as strip hCG are CLIA-waived and available over the counter or can be done in any physician’s office.) The Cardiac 200 is used in some physicians’ clinics, and Roche automated systems are used in physicians’ groups that have CLIA licenses.

Roche’s systems, Dodds says, are used in a majority of the top 10 heart and heart surgery hospitals, according to a US News & World Report August 2009 ranking of America’s best hospitals. Roche’s Troponin T assay is used in six of the top 10 hospitals, and proBNP II (NT-proBNP) is used in seven of the top 10.

Rapid Immunoassays

Leigh says Inverness’s Triage® MeterPro® Meter offers 16 immunoassays and provides results in about 15 minutes. The test menu includes cardiac biomarkers and toxicology, whole blood, plasma, or urine tests. It features customizable test panels; on-site training and implementation support; printed, displayed, and interfaceable results; and full connectivity support.

“The Triage Meter is very small and can be placed within patient care areas. Patients can be diagnosed right away when cardiac biomarkers are added to the patient workup. Many thousands of doctors worldwide use the Triage Meter because it’s so efficient and because they either don’t have access to large core lab analyzers or can’t risk waiting for delayed results. A number of hospital labs use the Triage Meter as a primary cardiac analyzer or as a backup to their larger instrument. It’s also frequently used by urgent care facilities,” he says.

The Triage Meter’s ease of use makes it the number one testing device for BNP, and Inverness has the only CLIA-waived BNP assay, Leigh says. The BNP assay doesn’t require a degreed medical technologist to run it—which is significant because of the decline in the number of lab techs—and it’s a fixed-cost instrument with no daily controls and a rerun rate of less than 1% versus the 5% to 10% rerun rate of a traditional lab analyzer.

Blood samples are drawn into a collection tube from a patient’s arm. A nurse then uncaps the tube and places a small sample on a test device such as Inverness’s Profiler Shortness of Breath Panel. This panel includes a D-dimer assay that tests for blood clots in the body, which, if present, can cause such thromboembolic events as pulmonary embolisms. Within minutes, the ED physician has results for all five markers, including troponin I, CK-MB, myoglobin, BNP, and D-dimer. Leigh says Inverness is the only company in the United States offering a cardiac immunoassay multimarker device.

Changes are coming for the Triage System to increase its menu and analytical performance. The device’s technology speeds up the diagnostic process significantly, Leigh notes, because it bypasses a lab system that is often slowed by numerous nonurgent routine tests. The device also helps alleviate ED overcrowding and costs by quickly helping physicians identify which patients with and without such classic symptoms as chest pain are actually having heart attacks. For instance, many women who present without classic crushing chest pain but with such other symptoms as back pain, sweating, and tingling in their left arm can be having heart attacks, which the Triage Meter can aid in identifying. Noncardiac patients can be excluded and discharged more rapidly.

The Triage TOX Drug Screen Panel is also administered in the ED to provide rapid screening for drugs of abuse, particularly for common medications such as Tylenol and cocaine, critical because some drugs are contraindicated for some cardiac medications.

Currently, Leigh says, the Triage Meter is used in about 63% of the approximately 5,000 US acute care hospitals and in many more thousands of facilities in the United States and worldwide.

Inverness also supplies the BNP test through Beckman Coulter, Brea, Calif, adds Michelle Fradette, marketing communications manager.

The Triage Meter is not found in the lab but is meant for immediate situations in the hospital, usually in the ED area that supports other testing that hospital labs may need to do when patients present symptoms, she adds. The Meter “tag teams” with labs in the hospital setting, so there’s no delay while waiting for other tests that take longer. Also, it’s about throughput, and the Triage Meter can rule out heart attacks and inform physicians about what testing they may need to have done in the lab.

And More Analyzers

Companies other than Inverness Medical— including Diagnostica Stago, Parsippany, NJ (mechanical clot detection)—offer automated analyzers for hemostasis/coagulation volume testing. Technologies from other companies—including Bayer, Pittsburgh; Abbott Diagnostics, Abbott Park, Ill; Beckman Coulter; and Sysmex America Inc, Mundelein, Ill—detect blood clotting time using light, Fradette says.

All of these instruments deal with larger-volume testing that takes longer because multiple patient samples must be collected, prepared, and run by the lab prior to results being communicated back to the physician and applied to the patient situation. As lab med techs face increasing demands for larger-volume testing, this can slow down results. In urgent situations the Triage monitor comes into play in the ED or even the physician’s office, where it can be determined whether or not a patient needs further lab work and/or should go to the hospital ED, she says.

Jeff Dahlen, PhD, vice president of clinical and regulatory affairs, Accumetrics, San Diego, says, “We’re on the verge of widespread awareness about the whole notion of antiplatelet medications and the fact that patients don’t respond equally to all of them. How do we better drive patient outcomes? We want to help doctors make the right decisions, and platelet function testing is a big part of that. The progress of cardiovascular disease increases with age.” And the rise in the number of older people as the Baby Boomer population ages, and the increase in obesity, are making cardiovascular problems more ubiquitous.

“We’re seeing more focus on the individual patient, and these tests help doctors determine how patients are responding to antiplatelet medications,” Dahlen says.

The specific element that Accumetrics’ cardiac testing devices address in the lab is platelet function testing, adds Dianah Schmidt, Accumetrics executive director, marketing services. From a patient’s perspective, cardiovascular disease is a big issue; more than 80 million people in the United States suffer from it in some form, and there were 830,000 deaths in the United States in 2006 from it, including 160,000 under the age of 65. Millions take antiplatelet drugs such as Plavix to combat the disease, she says.

But such medications don’t have the same effect on all patients, so lab tests are essential in telling physicians how patients are responding to these medications. And medications taken for different diseases can also impact one another, sometimes in negative ways, Schmidt says.

In hospital settings, platelet function or platelet reactivity tests are performed in catheterization labs—large testing areas with diagnostic imaging equipment used to support the catheterization procedure—where the effect of the antiplatelet medications given to patients can be determined. Other patient testing areas can include the operating room.

“Certain anti-clotting drugs may cause bleeding, which is not wanted during surgery. Has a surgery patient been off an anticlotting drug for long enough before surgery? This testing can help physicians understand any remaining antiplatelet effects, which could improve surgical patient care and reduce the length of their hospital stay,” Schmidt says. “By determining this, labs help improve patient care, and the testing done in a cath lab can prevent heart attack.”

Dahlen notes that EDs focus more on acute diagnostics and evaluating patients for potential acute myocardial infarction via troponin, CK-MB, and other testing. “There could be a role for platelet testing, though, because doctors need to know which medications patients are on, such as aspirin.”

For cardiac lab testing, Dahlen says that Accumetrics’ VerifyNow® System is offered with three tests, each specific to a type of antiplatelet medication: the VerifyNow Aspirin test, the VerifyNow P2Y12 test for Plavix and Effient anti-platelet medications, and the VerifyNow IIb/IIIa test for the intravenous glycoprotein IIb/IIIa inhibitors used in hospitals.

VerifyNow is a single-use, disposable, whole-blood testing device. It is inserted into the instrument and utilizes direct tube sampling to draw from a small tube of blood. Results are automatically displayed on the instrument screen. No user calibration or sample handling is necessary, and the devices include automatic quality controls. The instrument is about the size of a desk telephone, is portable, and has an assay port and a screen with a key pad. Results are provided in less than 5 minutes and are automatically displayed on-screen. The device can be used with an external printer, and there’s a connectivity option, Dahlen says.

Schmidt adds that the VerifyNow System has strong analytical performance and is easy to use, unlike other platelet function systems. It’s also distinguished by its strong correlation with other historical methods. “It’s in accordance with Accumetrics’ ‘easy, rapid, proven’ standards and is supported by more than 60 peer-reviewed publications,” she notes. And Dahlen says research and data overwhelmingly and consistently favor VerifyNow for its analytical and clinical performance in comparison with historical test methods.

“It’s less operator-dependent, requires no specialized operator training, is fast with shorter turnaround times, and there’s no sample handling,” Dahlen says. The product is used in 39 countries. In the United States, VerifyNow is in about one-third of the approximately 1,500 to 2,000 cath labs in hospital settings that do interventional procedures. It’s also used in the outpatient market, where Accumetrics is looking to expand its presence in the thousands of physicians’ office labs, Schmidt says.

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Gary Tufel is a contributing writer for CLP.