Case Series Of Evaluating Cardiac Calcium Score And Coronary CT Angiography (CCTA) In Asymptomatic Volunteers With No History Of Heart Disease In a Physician-Owned Freestanding Emergency Center (FEC) In Texas

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Henry Higgins, MD, Nathaniel Greenwood, DO, FACEP, Rena Salyer, DO Daniel Matulich, MD and Nichole Broussard RT(R)(CT) ARRT

 

Abstract:

64 Community volunteers participated in a free heart screening event at a physician owned freestanding emergency center in Texas. At the discretion of the attending emergency physician, 58 of these volunteers underwent cardiac calcium scoring. 6 of these volunteers also had coronary CT angiograms. 49.12% of the patients who underwent Calcium Scoring (CAC) were found to have coronary artery disease (CAD). 40.35% of patients who underwent CAC were referred for medical treatment and 8.62% were sent to cardiologist for likely stent placement or CABG. 50.88% of patients that underwent CAC were found to have a calcium score of zero and not referred for any further treatment.

 

Introduction:

In February of 2015 our physician owned emergency center in Texas offered a free heart screening event that was opened to everyone in the community. This event allowed our freestanding emergency center to train prn imaging staff as well as provide a free and very convenient heart screen for members of the community. The authors of this study were very interested to see how removing any cost barriers and scheduling barriers to heart screening might allow certain community members to seek preventative heart screening that may otherwise not undergo screening.

For reasons unknown to the authors the State of Texas does not condone any non-emergency activity within any physician owned freestanding emergency center. It must be made clear that this event was both a training event as well as a free community outreach that was meant to offer unprecedented access to this new CT screening technology.

The use of CT calcium scoring and coronary CT angiography in an emergency department is still very novel. These studies are typically done only in an out patient setting and under the guidance of non emergency physicians. It eludes the authors as to why more emergency physicians do not yet have access to this technology in their day to day practices. It could be that within the hospital setting there may be some disagreement among the specialties of radiology and cardiology which makes obtaining these studies in the emergency department impossible. It may also be that the imaging personnel fail to have the training on how to obtain these studies.

Most emergency physicians would likely find the calcium score and possibly CCTA to be of great value when evaluating patients for possible coronary disease. Unfortunately, coronary disease is very common and may present in very uncommon ways. Emergency physicians use many different protocols with which to rule out active coronary artery disease such as repeating cardiac enzymes at time intervals or simply admitting patients to observation and then obtaining in house stress tests. Having a tool such as CAC and or CCTA that would allow the emergency physician to better evaluate the existence of CAD would likely lead to more accurate and timely care.

Since our freestanding emergency center is owned by emergency physicians we have been able to use the CAC and CCTA technology on select patients who had risk factors for CAD. We have found several of our emergency patients who have had normal enzymes and ECG that ended up having significant CAD. We have only been open for a year and have had a slow volume but we have already sent three of our emergency patients for CABG and many others for stents and even more for medical treatment of CAD. In our experience the ability of being able to obtain CAC and CCTA (only when needed) on our patients has greatly enhanced our practice of emergency medicine.

In setting up our protocol’s for use of CAC and CCTA we have been very diligent that the CAC and CCTA not be overused. We only use it when we feel that there is a high risk of disease being present. We have had very high positivity rates using this approach. This high positivity rate in our emergency patients lead us to question what type of incidence of CAD that we may find in asymptomatic volunteers who did not have any history of CAD nor did they have any symptoms.

 

Case Series:

The staff of our freestanding emergency center alerted local area high school teachers and trainers, HOA members, and placed an ad on Facebook stating that we were offering free heart screening during the month of February “prevent a broken heart during Valentine’s day”. We set up scheduled exams on tuesday’ and thursdays. We decided to prolong the free community outreach into March as we had more volunteers than we had time slots for in February.

64 community volunteers participated in the event. Some of these volunteers were very low risk and felt by the attending emergency physician to not be appropriate for the CAC or CCTA. These volunteers instead underwent ECG and counseling regarding heart health and preventing heart disease. We did not wish to expose anyone to CT scan radiation unless they might benefit from undergoing the study.

The decision as to whether a volunteer would undergo CAC was made by both the emergency physician and the patient after discussing the technology, it’s limitations and risks and benefits. 57 of the volunteers underwent Calcium Scoring (CAC).

The GE 64 Light Speed cat scanner was used. Calcium scores were obtained by both computer generated algorithms and official radiological readings. The typical time from the CAC being ordered until the reading was available was around 20 minutes. The CCTA was done under gated conditions and was read by radiologists as well. When needed rate controlling medications (Cardizem, Lopressor) were used to near the CCTA patient’s pulse rate to 60. Several patients had their CCTA’s performed when their pulse was slightly above 70 and still yielded acceptable gated CCTA results. The typical time to obtain CCTA results varied from 1-4 hours as the on call radiologists were slow to read these at times. In our contract with the on-call radiologists these studies are to be read STAT but in the day to day operations of the radiologists their routine is to do the CCTA readings at a more leisurely out-patient pace. This is due to so few other facilities using CCTA in their ED and getting STAT readings. This confusion by the radiologists lead to multiple delayed CCTA readings. Volunteer patients undergoing CCTA were typically let go home and then called when the results were complete where by results were discussed and follow up arranged as needed. Prior to utilizing IV contrast on any of the volunteers, creatinine blood levels were drawn to ensure that the IV contrast was safe to give and not harm their kidney function.

If the calcium score (CAC) was zero the patients were warned that this does not absolutely rule out the presence or possibility of CAD but that it makes it very unlikely. If the patients CAC was less than 100 the patients were counseled regarding the presence of coronary artery disease and risk modifying behavior and told to follow up with their PCP to set up a strategy to monitor and prevent the progression of CAD. If the patient had a calcium score between 100-600 then the patients were offered a free CCTA. Based upon their CAC scores 7 patients where offered CCTA but one patient elected to follow up with a cardiologist while the remaining 6 underwent CCTA. If patient’s CAC was greater than 600 the patient was sent straight to an interventional cardiologist anticipating that a cardiac cath to be performed.

 

Results:

Of the 64 volunteers 7 of the volunteers were not offered CAC or CCTA due to their very low risk and 57 of the volunteers underwent CAC. The average age of the volunteers who under went CAC was 53 years. The Volunteer’s ages who underwent CAC ranged from 42 to 72 years of age. 31 of the volunteers who underwent CAC were male and 27 were female. All of the volunteers were not known to have any history of CAD. None of the volunteers had admitted to having any symptoms consistent with CAD. Many of these volunteers had failed to seek any preventative screening exams in the past due to being too busy working at full time employment. Most volunteers expressed sincere gratitude for having these exams done for free indicating that cost had also kept them from obtaining these preventative exams in the past.

Of the 57 volunteers that underwent CAC- 28 (49%) were found to have some degree of coronary artery disease (calcium present within the coronary arteries) and 29 (51%) were found to have a CAC of zero. The 19 volunteer patients (33%) who had a CAC of <100 were referred for medical treatment of CAD. The 7 patients (12%) who had a CAC between 100-600 were offered CCTA (one of these volunteers declined the CCTA and instead was sent to cardiology). The patients with CAC >600 were sent to interventional cardiology bypassing the CCTA.

 

Calcium Scores 0 1-100 100-600 > 600 Total
 

Number of Patients

 

29

 

19

 

7

 

2

 

57

 

Percent

 

51%

 

33%

 

12%

 

4%

 

100%

 

Of the 6 volunteers that underwent additional CCTA testing 5 were sent to interventional cardiology for either anticipated stent placements or CABG. The 2 patients who had CAC > 600 were also sent to the interventional cardiology for cath evaluation without undergoing CCTA. It was felt that having a calcium score >600 precluded a CCTA exam as this amount of calcium greatly diminishes the accuracy of the CCTA in patients who would be better examined through traditional cardiac cath techniques. Having a calcium score > 600 has been shown to be associated with an extremely high risk of having significantly stenotic coronary arteries. This high grade calcium load has been shown to cause artifact on the CCTA, obscuring the images.

 

Discussion:

This case series produced from a community outreach project and training session for imaging staff resulted in identifying coronary heart disease in 28 people (49% of the volunteers) who denied having any symptoms or history of CAD. The emergency physicians involved with this study were able to greatly enhance the positive predictive value of the CCTA by first using a calcium score in their decision as to whether to proceed with CCTA. The results of this case series suggest that using the CCTA in patients whose calcium score is between 100-600 may be of benefit when searching for significant CAD that may need intervention.

CCTA Sent for Medical Treatment Sent for Cardiac Cath or CABG Total Number of Patients
 

Number of Patients

 

1

 

5

 

6

 

Percent of CCTA Pts

 

17%

 

83%

 

Percent of CAC Pts

 

2%

 

9%

 

57

 

Percent of Volunteers

 

2%

 

8%

 

64

 

83% of the volunteers who underwent CCTA were found to have significant stenosis likely requiring either stent or CABG. Only one volunteer with a CAC between 100-600 failed to have significant CAD on CCTA (this outlier had a CAC =265).

23 (41%) of the 64 volunteers were found to have CAC between 1-100 and were sent for medical treatment of CAD. It is the duty of emergency physicians to also participate in disease prevention. Finding CAD prior to when it reaches a significant stenosis within the coronary arteries is thought to offer a window of opportunity for patients to utilize lifestyle changes and sometimes medication which may be very effective in postponing this development of critical CAD lesions. If more emergency physicians had access to CAC in their emergency departments it is likely that emergency physicians would be more successful in identifying early CAD disease and referring more patients to preventative treatment with either their PCP or cardiologist. This may have a large impact on many patients risk of having heart attacks.

Prevention campaigns are not new to emergency medicine. Public awareness campaigns for seat belt use, bicycle helmet use, drowsy driving, drunk driving, texting and driving have all been well participated in by those in emergency medicine. Emergency physicians have not been very involved in the screening aspects of CAD. EM docs typically meet CAD patients when they already have significant stenosis. Using the CAC in the ED will likely allow EM docs to become very involved in the screening and early detection of CAD thus helping to prevent STEMI scenarios.

Our facility utilizes a 64 slice GE Lightspeed cat scanner which is highly capable of performing the most highly technical angiograms such as CCTA. Many emergency departments are equipped with less capable CT scanners. CT scans that are only 4 slice, 8 slice 16 slice and 32 slice are all capable of performing the calcium score (CAC) when equipped with the proper software packages (work stations). There may be an opportunity for some emergency centers to gain the calcium scoring capability by upgrading or replacing only their existing workstation which can be done at a nominal cost. Having the calcium score alone may be of great use in both CAD diagnosis as well as screening activity.

5 (8%) of the 64 volunteers were found to have CAD significant enough to warrant referral for intervention. This study was done on asymptomatic volunteers. When considering the otherwise healthy volunteer in this study to the typical emergency room patient with chest pain it is very likely that if CAC and CCTA were used on strictly emergency room patients with chest pain that the percentage of positive results for both CAC and CCTA would be much higher than what was found in this community outreach project. Using the CAC and CCTA would likely yield faster dispositions for these patients and more accurate diagnosis. Furthermore, by including the CAC and CCTA in select patient’s chest pain work ups the likely hood of missing CAD as the diagnosis would be greatly reduced.

This was an un-expectantly high % of positives for this community outreach project in asymptomatic individuals. Many of the participants in this study admitted to not undergoing health maintenance and preventive medicine examination in the past due to cost constraints and not having time to get these studies preauthorized and scheduled. The participants in this study were comprised primarily of teachers, coaches, mailmen, business owners, bankers, fathers, mothers and etc in a relatively healthy community where obesity and inactivity are very infrequent. A vast majority of the volunteers were well employed, likely had commercial insurance and maintained very healthy and active lifestyles. It was surprising that so much CAD was identified in this group of people.

In the era of “patient directed care” where by the cost of all healthcare is being shifted to the consumer via copays, coinsurance and deductibles the medical profession has already witnessed a decrease in patients obtaining health maintenance and preventive medicine exams and screens. Less and less patients will undergo health screening and health maintenance as insurance companies create more financial and clerical difficulty hurdles to obtaining healthcare. The emergency department will likely become a much more significant provider of health screening as the “patient directed care” cost shifting becomes more and more prevalent.

 

Conclusion:

The use of Calcium Scoring and Coronary CT Angiography in free standing emergency centers and hospital based emergency departments is feasible and allows for a higher degree of accurate diagnosis and screening for coronary heart disease. By adhering to clinical guidelines that utilize risk assessment the use of this technology in Free-Standing ERs and Centers may also offer cost savings, less missed diagnosis, and increased patient satisfaction.

Emergency physicians who are allowed to utilize this technology and have it available have been shown to have a significant impact upon coronary artery disease detection even in asymptomatic volunteers. The authors conclude that more widespread use of this technology across the broad spectrum of emergency medicine will likely have a significant positive impact on public health especially in regard to patients who present to the emergency department complaining of chest pain.

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