Intensive use of radiology in chest pain ED patients saves $5.2 million
Suspected AMI ruled out through advanced diagnostic techniques
During an 18-month period, prompt radiology imaging tests saved one Florida hospital $5.2 million, reported Jack Ziffer, MD, PhD, director of cardiac imaging at the Chest Pain Center at Baptist Hospital in Miami and colleagues at the annual meeting of the Radiological Society of North America in Chicago, this past December.
The money saved was associated with reducing admissions of those chest pain patients who, it turned out, were not having a heart attack after all. Nuclear testing combined with multidisciplinary coordination before admission reduced to less than two-tenths of 1% the number of misdiagnosed heart attacks at Baptist. Before setting up the scanning program, 40% of chest pain patients were admitted; today that percentage is 12.
For that study reported in Chicago, investigators looked at nearly 5,000 emergency department (ED) chest pain patients over an 18-month period. About 88% of them eventually were discharged without being admitted. Average length of stay in the ED was 12 hours, during which time, depending upon symptoms, clinicians took a history and administered a chest X-ray, an EKG, and at least one additional radiology test - single-photon emission computed tomography (SPECT) imaging, ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), or ventilation-perfusion (VQ) scan. (See table of ECG findings suggestive of AMI, p. 110.)
Patients were evaluated and placed in one of four categories:
· Those known to be having an acute myocardial infarction (AMI) based on EKG and history - about 10% - were referred immediately for treatment. (See Killip Classification, p. 111.)
· Those thought to have other cardiovascular problems such as aortic dissection or pulmonary emboli were referred for further appropriate imaging.
· Those thought to have gastrointestinal or musculoskeletal problems were referred for further imaging.
· Those with normal EKGs who were suspected of having AMI or pending AMI had SPECT imaging which shows whether the patient has had an AMI and whether he or she has heart disease.
Two-thirds of study participants fell into that group, of which three-quarters were found to have normal heart function and discharged. "Despite intensive use of radiology services," stated Ziffer, "the overall cost of patient care was reduced by $5.2 million in this group alone."
'How much does it hurt?' just doesn't do it
It's no news that the mis- or under-diagnosis of AMI is a costly problem. EKGs and blood tests are often inconclusive, and questions such as "How much chest pain did you have?" and "How much does it hurt?" seldom receive satisfying, informative answers. Nuclear imaging scans can remove some of the doubt associated with chest pain and can also save lives and money by efficiently detecting heart disease in patients before a first or second AMI strikes.
Treating a heart attack in the ED typically costs about $50,000 overall. A typical charge for a myocardial perfusion SPECT imaging study is $1,034, and the charge is reimbursed by most insurance companies.
Patients coming into the Chest Pain Center at Baptist are routinely given nuclear medicine drugs right away, then triaged and given EKGs. Technetium Tc99m Sestamibi (Merck's Cardiolite) is that facility's heart imaging agent of choice. If standard tests fail to confirm or rule out AMI, the radiologist steps in to look for abnormal blood flow to the heart. If images show no problems, patients are discharged.
"We use a SPECT scan only on patients who present with active chest pain," says Craig McColl, nurse manager of the emergency center at Baptist. "We've seen a high correlation between positive findings on the SPECT scan and active chest pain. If a patient doesn't have active chest pain on arrival, we give him or her a thallium stress test instead after they go through the chest pain protocol. That helps us to reproduce the chest pain they've experienced."
At the annual meeting of the Society of Nuclear Medicine in Toronto last June, Baptist investigators presented research that showed nuclear imaging also can substantially reduce the risk of discharged patients having an out-of-hospital heart attack. Ziffer and colleagues ran a two-year study of 2,700 patients who returned to the ED with acute chest pain. Those who had an inconclusive EKG underwent SPECT to see if heart disease was present. Under normal circumstances those patients would have been discharged. The likelihood of AMI in discharged study participants whose SPECT was normal was only one in 770. Under routine circumstances, a patient discharged after an inconclusive EKG had a one in 56 chance of heart attack. Ziffer made the statement that when heart disease is not correctly diagnosed in the ED, patients have a significant probability of dying from their AMIs. Nuclear imaging in the ED enabled the investigators to detect disease before it caused a heart attack.
But what about expense? In that study, total costs were $2,940 to save one year of life in patients who may not have discovered their disease until later when a life-threatening AMI struck. (By way of comparison, it costs $67,000 to save one year of life using passenger side airbags in cars.)
A third study conducted by Ziffer and colleagues, also presented at the conference, focused on nearly 3,000 ED patients whose chest pain had gone away by the time they got to the hospital. That category of patients accounts for three-quarters of all chest pain patients seen in EDs, and they are typically sent home after an EKG that is normal or inconclusive. In that study, 98% of all coronary artery disease cases in study participants whose EKGs were normal or inconclusive were detected by either a nuclear medicine rest scan alone or a rest scan combined with a nuclear medicine stress test.
"Many patients who have had a complete resolution of their chest pain still have underlying coronary artery disease," wrote Ziffer. Rest perfusion imaging is not sensitive for detecting the disease, and that puts patients at greater risk - because they are showing no symptoms they think their condition has gone away. Stress imaging identifies those who require additional treatment.
Stemming misdiagnosed AMIs
"Nuclear medicine is absolutely beneficial to AMI diagnosis," says Robert Eisner, PhD, co-director of nuclear cardiology at Crawford-Long Hospital in Atlanta. "Even the smallest community hospital has a SPECT machine. Its use is widespread, so why not use the technology for these chest pain patients?" According to Eisner, the largest general hospital in Georgia, 837-bed Grady Memorial in Atlanta, has its SPECT facility a few flights away from the ED, but he says some hospitals have the technology adjacent to the workup room of the ED.
Two factors should be considered with nuclear imaging for AMI. First, the ED staff have to become accustomed to working with nuclear medicine. "It does require some expertise," says Eisner. Second, the key to using radiologic imaging effectively is having a radiologist on call 24 hours a day. "The nuclear technologists have to be on call night and day so they can come in and do the studies or inject the radioisotopes. That factor has prevented this technique from becoming more popular than it is," he says.
Edward DiBella, PhD, a researcher in the department of radiology at the University of Utah Health Sciences Center in Salt Lake City says his organization just recently put nuclear facilities within its ED. "SPECT is expensive," he says, "but not when it's compared to MRI or PET [positron emission tomography] scanning."
SPECT compares well to cath
Capital outlay for the technology varies. A refurbished single-head camera computer system might cost $150,000 or less, or you can spend up to $500,000 for a newer state-of-the-art system. "The older refurbished systems will do the job," says Eisner.
How does nuclear imaging for cardiac diagnosis compare with blood tests? "Blood tests such as those for troponin and creatine kinase (CK-MB) just show whether the patient has had a heart attack - whether heart tissue has died," says DiBella. "SPECT tells you that, and where. It localizes the information." If all you need to know is whether there was an event, the other tools would be more appropriate.
"SPECT even compares favorably to cath in some cases," says DiBella. "You can see blockages on the cath image, but you don't know if opening them up will help. The muscle may be just scar tissue. SPECT gives you an idea of whether the tissue is still alive - it has minimal blood flow - but hibernating." For those reasons, SPECT can be complementary to a catheterization.
"SPECT is favorable to ultrasound or MRI," he says, "because those show you the anatomy, and with SPECT you see a picture of blood flow and viability."
A quarter of the 4 million people who come to America's EDs complaining of chest pain each year are either having or on the verge of having an AMI. Most have gallstones, hernia, or such injuries as broken ribs. Five percent have life-threatening conditions such as pulmonary emboli or aortic dissection.
Typically, 3% to 5% of chest pain patients are misdiagnosed and mistakenly sent home from EDs, sometimes resulting in costly litigious actions later. On the other side of the coin, as many as 70% are admitted without need. If an accurate diagnosis can be made quickly, in a chest pain unit before a patient is admitted, the length of stay is cut regardless of outcome because the patient is away from the time-consuming hospital system. A discharge can be delayed between eight and 18 hours just because of hospital routine.
Reference
1. Tatum JL, Jesse RL, Kontos MC, et al. Comprehensive strategy for the evaluation and triage of the chest pain patient. Ann Emer Med 1997;29:116-125.
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