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A New Standard of Care for Cardiac Cases

By Gene Moen

Recent advances in detectingdamage to heart muscle havecreated a new standard of carefor treating patients in the emergencyroom for symptoms of heart disease. Thestandard of four years ago employed a“rule out myocardial infarction” (MI)strategy that was based on insensitiveassays by today’s standards. Patientsreporting to emergency rooms andcomplaining of chest pain were oftendiagnosed with gastrointestinal upsetor anxiety attacks and sent home withinsufficient consideration of possibleheart disease (see our article in TRIALNEWS, January 1998, A fatal standardof care for heart attack victims). Someof these patients would succumb to afatal heart attack within days of theiremergency room visit.

Today, patients presenting to theemergency room with a variety ofsymptoms of heart disease are evaluatedusing more sensitive indicators ofdamage to heart muscle, and theyare stratified into groups with highand low risk of mortality from heartdisease. Many hospitals have a chestpain unit (CPU) to evaluate patientsat low risk for heart disease. Theobjective of a CPU is to reduce theinadvertent release of patients withacute coronary syndrome and to reducethe number of healthy patients admittedto the hospital’s coronary care unit(CCU). The CPU may be a physicalplace in the hospital with a room or beddesignated for patients complainingof chest pain or it may be a virtualunit within the emergency room witha specific protocol for evaluation ofchest pain patients and employing preassignedhealthcare providers.

The ability of healthcare providersto identify a wider group of patients withunstable angina, or acute myocardialinfarction at risk of sudden death, hasresulted in a new term to designatethis group – acute coronary syndrome(ACS). A physician may include ACSin the differential diagnosis if the patientcomplains of chest pain, sweating,shortness of breath, epigastric pain,pain in the jaw, shoulder, or arm,light-headedness, or nausea. Pain thatis positional or reproducible withpalpation is less likely to associatedwith ACS. The absence of chest painalone when other symptoms of ACS arepresent is not good reason to removeACS from the differential diagnosis.

An attorney whose client hassuffered a debilitating heart attack orwhose client has lost a loved one aftera visit to the emergency room forchest pain should examine the medicalrecords and interview his client orfamily to determine whether theemergency room physicians performedthe currently accepted proceduresand tests to diagnose ischemic heartdisease. Those procedures and testsinclude (1) a brief history and physicalincluding an assessment of risk factorsfor heart disease, (2) interpretation ofan electrocardiogram (EKG or ECG),(3) establish IV access, (4) administeroxygen, (5) give aspirin, and (6) examinelaboratory values including assessmentof serum levels of biochemical markersfor cardiac muscle death. Based on therisk assessment, the physician shouldadminister nitroglycerine, beta blockers,fibrinolytics, thrombolytics, or heparin.If the providers have not done a thoroughjob of evaluating your client for ischemicheart disease, they may have cheatedhim/her of a chance to recover to normalhealth through angioplasty or coronaryartery bypass grafting (CABG).

The risk is high that a patientdiagnosed with ACS will sufferserious consequences. Cardiovasculardisease caused 949,619 deaths in theUnited States in 1998. Almost half ofthose deaths (459,841) were caused bycoronary (ischemic) heart disease (CHD).CHD is the single largest killer ofAmericans of either sex, but if caughtearly, patients with CHD can be returnedto normal through coronary arterybypass surgery or through angioplasty.The lifetime risk of developing CHDafter age 40 is 49 percent for men and32 percent for women. American HeartAssociation. 2001 Heart and StrokeStatistical Update. Dallas, Texas:American Heart Association, 2000.

The most serious risk of coronaryheart disease is sudden death caused byheart failure. Ninety percent of suddendeath victims have two or moremajor coronary arteries narrowed bycholesterol plaques (atherosclerosis). Theperson dies because a clot plugs anartery already narrowed by cholesterolplaques. The area of the heart suppliedby that artery is starved for blood(ischemia) and the heart muscle (myocardium)stops contracting and eventuallydies (myocardial infarction).The heart beats faster (tachycardia)to compensate for the lost musclefunction and subsequently the rhythmicbeat patterns of the heart give way touncoordinated contractions (ventricularfibrillation) and cardiac arrest (asystole).

The chance that a person in cardiacarrest will survive diminishes by 7 to10 percent for each passing minute.Given the risk of sudden death, thestandard of care requires physiciansand nurses in emergency rooms to bewell prepared to promptly diagnoseand treat patients with symptoms ofcoronary heart disease.

Recent Advances in Diagnosing

Ischemic Heart DiseaseEmergency room personnelhave new tools to help them identifypatients at risk of sudden death.The past few years have witnessed arevolution in the use of proteinisoforms found specifically in theheart muscle as sensitive markersfor damage. When the heart musclecells die as the result of ischemia,their contents are released into theblood stream. Muscle proteins are notordinarily found in the bloodstreamand their presence there is a goodmarker for muscle cell death. Somemuscle proteins exist in forms that areunique to heart muscles. The presence ofthese cardiac specific forms of muscleproteins in the blood is a marker formyocardial infarction. The proteinmarkers include heart specific formsof troponin (cTnT, cTnI), creatinekinase (CK-MB), and myoglobin.

Troponin is a protein made up ofthree subunits, two of which exist incardiac-specific forms. A minor concentrationelevation of one of thesecardiac troponin subunits has beenreported to predict increased risk fordeath or recurrent ischemic events.

The test for serum levels oftroponin presents many advantagesover other diagnostic tools for acutecardiac syndrome. First, the presenceof even microscopic areas of cell deathcan be detected. The physician candetect the very earliest effects ofischemic heart disease and treat thepatient before significant damageis done to the patient’s heart muscle.

Second, troponin is released slowlyover a much longer time period thanother markers of cell death. In one study,almost half of the cardiac troponinpositive patients tested positive atadmission, with 78% and 100% testingpositive at four and eight hours,respectively. This broad windowfor detecting troponin increases theprobability that a physician will detectheart disease.

Third, test kits for cardiac troponinare available that can be used in medicalfacilities that do not have large centrallaboratories. These kits are called pointof care tests. The accuracy of resultsfrom point of care test kits has beenreported to compare favorably to resultsobtained with central laboratory tests.Small or isolated clinics and hospitalshave no excuse for failing to employthe troponin test.

Facilities with central laboratoriescan also take advantage of point of caretests to speed results. The point ofcare test can provide results in as littleas 15 minutes compared to the two tothree hours it takes to get results froma large central laboratory. Speed is ofthe essence when a patient may needemergency catheterization to avoid afatal heart attack.

A second marker for heart musclecell death is creatine kinase that is anenzyme found in all muscles. Heartmuscle contains a specific isoform ofcreatine kinase that is designated asCK-MB. Normal serum has a higherbackground concentration of CK-MBthan it does of troponin and CK-MB isreleased over a narrower time periodfollowing heart muscle cell death thantroponin. CK-MB is no longer the goldstandard for evaluating patients possiblysuffering from myocardial injury,and exclusion of an acute myocardialinfarction (AMI) is not satisfactoryinitial risk stratification of a patientwith acute coronary syndrome.

The new markers for myocardialinjury have not displaced the first stepsin risk stratification that we describepreviously (TRIAL NEWS, January,1998). However, there is renewed emphasison detailed interpretation ofthe initial EKG as an important step inevaluating a patient possibly sufferingfrom acute coronary syndrome. Newresearch indicates that certain featuresof an EKG are strong predictors offuture bad outcomes. Those featuresinclude ST segment elevation or depressionand T wave inversion. AnEKG must be taken early when ACS isin the differential diagnosis, but moreimportantly, it must be interpretedimmediately. Most EKGs will have acomputer interpretation automaticallyprinted on the printout. Although thecomputer may over-interpret the EKGand is seldom used by itself as a basis fordiagnosis, the computer interpretationcan be a red flag that mandates the providerto seek a prompt interpretationA New Standard Of Care For Cardiac Cases continuedby a cardiologist. In this day and age of faxmachines, digital image scanners, ande-mail attachments, even small healthcarefacilities should have a cardiologistavailable to evaluate an EKG.

An attorney evaluating the medicalrecords in a new case involving suddendeath should look for the followinginformation:

(1) What were the patient’s physical symptoms and history?

In our 1998 TRIAL NEWS article,we identified the initial symptomatologyof angina and the patient’s age as valuablepredictive tools for assessing risk ofbad outcomes from heart disease. Thesame is true today. A patient with typicalangina (chest pain that reproduciblyis induced by exercise and relieved byrest), and who is more than 40 yearsold has a very high probability thatone or more of his coronary arteriesare seriously narrowed. A patient withtypical angina should be evaluated forcoronary heart disease immediately.

If a patient in an emergency roomhas the symptoms of typical angina, heis a serious candidate for catheterizationregardless of his risk factors. However,risk factors are an important tool forattorneys in portraying whether a healthcareprovider was reasonably prudentin sending the victim home. Victims ofsudden death often have multiple riskfactors for ACS. For example, askingthe defendant healthcare provider if sheknew at the time she sent the victimhome that the victim was 50 years old,hypertensive, a smoker, had a familyhistory of coronary disease, had previouslycomplained of fatigue, was overweight,and lead a sedentary life style in additionto his immediate complaints of chestpain induced by exercise, will create areal question about the reasonablenessand prudence of the provider’s care.

Risk factors are also importantbecause healthcare providers oftenconcentrate unreasonably on theabsence of a single risk factor. Forexample the victim may have been asmoker with a family history of suddendeath who complained of fatigue andwas overweight, but the healthcareprovider might focus on the fact thathe was only 30 years old. While it istrue that the risk of coronary heartdisease increases after age 40, theabsence of a single risk factor alone, orfor that matter the absence of all riskfactors, is no justification by itself forsending an ACS patient home.

(2) Was an EKG taken and immediately interpreted?

Taking and interpreting an EKG is standard of care. The purpose of taking an EKG is so that a cardiologist can interpret it and decide whether the patient is experiencing ischemic heart disease or has suffered a myocardial infarction.

A normal result on an EKG, byitself, should not cause the healthcareproviders to send an ACS patient home.Ischemic events are often episodic.If an EKG is taken between episodes ofischemia, it may be normal. The simplerule is that an EKG that is positive forheart disease is extremely importantand an EKG that is negative should notbe relied on as the sole reason to releasean ACS patient. The same rule appliesto an EKG taken in the context of anexercise treadmill test (ETT). However,a physician can include a normal EKGin conjunction with other diagnostictools to conclude that a patient has alow risk of mortality from heart disease.

(3) Were serum levels of troponin taken?

The new more sensitive test for cardiac troponin has revolutionized the evaluation of patient risk of coronary heart disease. In our 1998 TRIAL NEWS article, we cited a National Institutes of Health study that concluded that tests for muscle enzymes in the blood were of little value for evaluation of patients in the emergency room suffering acute chest pain.

In contrast, today, the standardof care for detection of myocardialinfarction is the cardiac troponin test. Apatient with elevated cardiac troponinlevels should be considered to havecoronary heart disease until provenotherwise regardless of whether hissymptoms of chest pain are atypicaland his EKG is normal.

(4) Was the patient evaluated systematically over a period of several hours for the purposes of stratifying his risk of a future bad outcome, or was he simply evaluated for “rule out MI” and sent home?

Risk stratification is the standardof care. It is no longer appropriate to“rule out myocardial infarction” andthen send the patient home. Troponinlevels and an EKG should be takenwhen the patient first arrives at theemergency room and at 4 and 8 hoursafter arrival.

(5) Based on the risk stratification, were appropriate follow up tests or treatments done?

ACS patients often suffer chest painepisodes that become more frequentand worsen as the patient nears a heartattack. A physician may interrupt theprogression of pain episodes by treatingthe patient with nitroglycerine to reducepain and to lower blood pressure orwith morphine to reduce pain. Heparincan be given to inhibit the formation ofblood clots that could cause myocardialinfarction. Thrombolytics may be givento destroy blood clots and possiblyre-establish blood flow to ischemicareas of the heart muscle.

Physicians should employ severaladvanced tests to stratify ACS patientsinto high and low risk groups. SerialEKGs and serial troponin levels are thestandard of care for ACS patients. Anattorney should expect to see exercisetreadmill tests, with or without imaging,and, if the patient is placed in a highrisk group, he should be evaluated forartery disease by angiography .

The exercise treadmill test is stillemployed because it is inexpensive, and apositive result indicating coronaryheart disease is very reliable. The valueof exercise treadmill testing is stilldebated because it may not add verymuch to the prognostic value of asimple EKG and because it missessignificant numbers of patients withcoronary heart disease. However, becauseof the value of a positive result, exercisetreadmill testing remains the standardof care.

Blood flow over the surface of theheart may be observed by imagingthe radioactive tracer, technetium 99m,while the patient is either resting orperforming an exercise treadmilltest. Imaging with technetium is nota stand-alone test because it missestoo many patients with coronary heartdisease and because its success is highlydependent on the skill of the physicianin performing and interpreting thetests. But technetium imaging adds tothe sensitivity of an exercise treadmilltest and has been shown to be costeffectivein further stratifying low riskACS patients.

Angiography remains the goldstandard for diagnosing coronaryheart disease. Patients with EKG,troponin, or exercise treadmill teststhat indicate coronary heart diseaseas well as patients with typical anginashould be evaluated by angiography.

Conclusion

The standard of care for evaluatingpatients with possible coronary arterydisease is evolving and changing. Almostevery month there is a new researcharticle in a medical journal describingchanges in evaluating and treating suchpatients. Unfortunately, there is oftena “time gap” between the emergence ofnew techniques or procedures and theiradoption as a routine by emergencycare or primary care physicians.

In reviewing a potential caseinvolving death or injury from delayin diagnosing coronary disease, theattorney must keep in mind that thestandard of care is not that which isfrequently or even commonly done inthe medical community. The medicalnegligence statute, RCW 70.70.040(1),requires proof that the physician didnot “exercise the degree of skill, careand learning expected of a reasonablyprudent [physician], in the State ofWashington, acting in the same orsimilar circumstances. The WashingtonSupreme Court held in Harris v.Groth, 99 Wn.2d 438 (1983), that the“expectations” are those of society,not those of the medical community.What other physicians do may beevidence of the standard of care, but itis not dispositive (See WPI 105.1).

If a provider is assuming the roleof evaluating patients with possiblecoronary artery disease, it is a reasonablesocietal expectation that the providerbe aware of the current and acceptedprocedures for doing so. If he is not,the patient who entrusts his care tohim may suffer the consequences.

Eugene M. Moen, J.D. is a partner inthe Seattle firm of Chemnick, Moen &Greenstreet, which limits its practice tomedical negligence and drug liabilityclaims. Roger J. Leslie, Ph.D., J.D., is ofcounsel to the firm and handles casesinvolving medical and other complexscientific issues.

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