Chest Pain: The Other Diagnoses

   At 0730 on December 24 you and your partner are called to respond to a 59-year-old male office worker with a history of mild, well-controlled hypertension who is complaining of chest pain. As you head for the ambulance, you turn to your partner and say, "Well, there won't be much guesswork on this call. It has to be cardiac-related." Your partner agrees. You are both aware of the statistics: Heart attacks are more common in the morning and during holiday times, when people tend to eat and drink too much and become more stressed. Besides that, your patient is male, middle-aged and has hypertension. It's a no-brainer, right? Maybe...maybe not!

   Upon your arrival, you find him sitting in a chair and appearing to be in slight discomfort. His vital signs include a blood pressure of 142/80, pulse of 84 and regular respiratory rate of 14/minute and a pulse oximetry of 97% on room air. He denies any such episodes in the past, and describes the pain as being substernal and burning in nature. He complains of slight nausea, but denies vomiting, shortness of breath or diaphoresis.

   In accordance with local protocol, you run a 12-lead ECG strip, which your partner interprets as normal. The machine's interpretation agrees with your partner. An intravenous line is started, and the patient is given four 81 mg aspirin tablets to chew, a sublingual nitroglycerin spray and 25 mg of metoprolol orally. A repeat set of vital signs shows little change, and the patient is transported to the nearest hospital emergency department for further evaluation.

Discussion

   This is a scenario that occurs multiple times each day in virtually every region of the country. In most places, the responding providers would have followed this exact sequence of evaluation and medication administration, or a comparable one, because the working diagnosis would be either acute myocardial infarction (AMI), unstable angina or the newer term, "acute coronary syndrome" (ACS). The reality, though, is that in many of these cases, this diagnosis would turn out to be incorrect.

   As a prehospital provider, it is very helpful, while following the algorithm in your region for chest pain, to consider some of the other possible causes of chest pain. This serves not only to prevent interventions that are unnecessary, but also to enable you to develop a more academic thought process. This type of approach will certainly be of value on the next call and will also help keep you sharp.

The "Other" Diagnoses

   Some of the non-cardiac causes of chest pain are common and some are rare, but all of them may cause patients to complain of chest pain. As is often true in medicine, the proper treatment for some of these disorders may, in fact, be detrimental in others. This reinforces the need for an accurate diagnosis prior to instituting treatment.

GERD (Gastroesophageal Reflux Disorder)

   This is the most common gastrointestinal disease in the United States, and it is not surprising that a disease which causes "heartburn" can be mistaken for cardiac disease. GERD is caused by increased production of acid in the stomach and regurgitation of that acid into the esophagus. In many cases, people with this condition develop a burning substernal chest discomfort with radiation toward the neck, especially after eating or when reclining. They may also experience nausea, hoarseness and/or sore throat. The symptoms are improved by the use of antacids.

   One way to attempt to determine if GERD is the cause of the patient's symptoms is to obtain a complete list of the patient's medications. Often they will be taking medication to decrease the amount of acid produced by the stomach. These medications might include H2 blockers (Zantac, Pepcid, Tagamet or Axid) or proton pump inhibitors (Nexium, Aciphex, Protonix or Prilosec). Additional history would also help to distinguish GERD from cardiac disease. Does the pain occur when recumbent? Did the pain begin after a large meal? Does the pain improve after using an antacid?

Costochondritis

   The ribs that make up the chest wall consist of bony tissue in the posterior portion that merges into cartilage at approximately the anterior axillary line; the cartilage then connects the ribs to the sternum. At times, this point of connection (the costochondral junction) becomes inflamed and causes pain. This clinical entity is a very common chest wall cause of chest pain and is often found in adolescents under age 21, but it also may occur in adults, which could lead to confusion in the diagnosis of chest pain. Costochondritis is more common in females, with a female to male ratio of 70:30.

   The primary way to distinguish chest pain caused by costochondritis from cardiac chest pain is that in the former, the pain tends to be reproducible by palpating over the inflamed area of the chest wall. This is usually treated with antiinflammatory medications and localized heat or cold applications.

Pneumonia and Pleurisy

   Pneumonia is an infectious disease of the lungs that can occur at any age. It can be caused by a wide variety of organisms, including bacteria, viruses, fungi, etc. Pleurisy is an inflammatory process which strikes the double-layered pleural membrane that surrounds the lungs. When the pleural membrane is affected, either directly by pleurisy or indirectly by pneumonia, the resulting inflammation can lead to a complaint of chest pain. This occurs because each breath the patient takes causes the inflamed pleural sheets to rub together, stimulating pain receptors at the site. This rubbing together can also be caused when the pneumonia patient coughs, again causing pain. As is often the case, pain can produce nausea and vomiting, which further confuses the clinical picture.

   The decision-making process for the EMS provider involves distinguishing this pleuritic chest pain from that with a cardiac origin. It is crucial to ask the patient if the pain is continuous or only present during breathing or coughing. While a patient with pneumonia requires antibiotics and the pleurisy patient may need antiinflammatory medication, neither of these treatments will benefit the cardiac patient.

Pneumothorax

   Spontaneous pneumothorax occurs in people who have some congenital abnormality of the lung. This abnormality is often a bleb, or bubble, on the lung. Occasionally, the bleb can rupture, releasing air from inside the lung into the pleural space. As the amount of air in this space increases, it causes the lung to collapse...a pneumothorax.

   Patients who develop this condition are often young males, and are usually tall and thin. However, people who do not fit this picture can also get a pneumothorax. Most patients complain of chest pain on the affected side, which is often pleuritic (the pain increases with respirations) in nature. Interestingly, dyspnea is not typically a major symptom, although it may be present to a small degree.

   In order to distinguish these patients from those with cardiac chest pain, it is crucial to take a careful history. The symptoms of pneumothorax usually begin very suddenly and often follow a strong cough or sneeze. The physical examination will also help you to distinguish the two clinical problems. On auscultation of the lungs in pneumothorax, you will hear decreased breath sounds on the affected side. This decrease will be even more apparent when comparing the affected side to the unaffected one. Of course, a quiet environment is helpful, but this is difficult to obtain in the back of an ambulance. Pneumothorax may be treated by watchful waiting or by inserting a chest tube. The treatment choice depends on how large the pneumothorax is and how symptomatic the patient.

Pulmonary Embolism

   Pulmonary embolism (PE) is one of the most common findings in patients who die while in the hospital. An autopsy indicates the significance of this clinical problem. A PE occurs when a blood clot forms, usually in the veins of the legs or pelvis, then breaks off and travels to the lung. The clot lodges within one of the branches of the pulmonary artery, obstructing blood flow to a region of the lung, which can then not participate in gas exchange, and the affected lung tissue dies because of inadequate oxygen supply.

   Patients who develop a PE may often complain of chest pain that is pleuritic in nature. Dyspnea may also be a prominent symptom, along with a cough that may produce rust-colored sputum. A major challenge to making the diagnosis is that many symptoms of PE are non-specific, and often, very few symptoms are present.

   Again, taking a careful history may prove invaluable. Patients who develop a PE are frequently those who are not able to move about normally (e.g., following many types of surgery, a stroke, or an injury to the legs). This sedentary condition places the patient at increased risk for blood clot formation. Additionally, some patients have a predisposition for abnormal blood clotting, such as patients with blood disorders or women who are pregnant. The important thing is to always consider the possibility that a PE is the cause of the patient's symptoms.

Pericarditis

   The heart is surrounded by a double membrane called the pericardium, which contains a small amount of fluid that serves as a lubricant. At times, this membrane becomes inflamed; this inflammatory reaction is pericarditis. Patients with this condition often complain of chest pain, which may be associated with dyspnea. This chest pain may lead the EMS provider to consider coronary artery disease (CAD) as the culprit.

   One characteristic that may be useful in separating these two conditions is that the pain associated with pericarditis is often worse when lying flat and improves when sitting upright. Additionally, the ECG may demonstrate diffuse elevation of the ST segments. This diffuse nature of the changes on ECG is more indicative of pericarditis than CAD, even though the appearance of the tracing can be alarming.

   Pericarditis is generally treated with analgesics and antiinflammatory medications. Occasionally the amount of fluid within the pericardial sac increases dramatically (pericardial effusion). As the fluid increases in quantity, the pressure within the sac also increases. This increased pressure can inhibit the pumping action of the heart and decrease cardiac output (pericardial tamponade), which can rapidly escalate into a true medical emergency that may be life-threatening.

Aortic Dissection

   On occasion, the lining (intima) of the thoracic aorta develops a weakness that permits the blood flowing within to develop a false channel. The blood, propelled by its own pressure, can continue to separate the layers of the aorta as it extends distally. This false channel can then either re-enter the normal lumen of the aorta or open outside of the aorta. Many people refer to this condition as a dissecting aortic aneurysm, but this is really not a correct term, since pathophysiologically, an aneurysm is a different entity.

   Patients with aortic dissection typically complain of chest pain that may be associated with shortness of breath. One fact that may help to distinguish this condition from CAD and AMI is that, with aortic dissection, the pain often radiates to the back and is described as a tearing sensation. In fact, many of these patients see chiropractors and orthopedists for their back pain without a diagnosis being made. The condition comes to light when a physician eventually orders either a CT or an MRI of the chest. Some of these patients only require watchful waiting, while others may require urgent surgical intervention. Distinguishing aortic dissection from ACS is very important, because aortic dissection patients should not be given anticoagulants or clot-buster medications, as these may lead to a fatal outcome.

Herpes Zoster

   Herpes zoster, commonly referred to as "shingles," is a disease caused by the same herpes organism that causes chicken pox (varicella). Following a clinical case of chicken pox (usually as a child or young adult), the herpes organism can remain dormant in the nerve roots, sometimes for many years. At some future point, a stressor (physical, emotional or other inciting factor) will cause these organisms to become reactivated in a single nerve root. Early symptoms of zoster include pain along the path of the affected nerve root. When that nerve root is in the thoracic region, the pain may mimic cardiac chest pain.

   Following the onset of pain, a vesicular rash develops along the affected nerve root distribution. Symptoms of zoster are nearly always unilateral.

   Prior to the rash outbreak, it can be very difficult to distinguish the pain of zoster from cardiac chest pain, especially when the involved nerve root is on the left side of the chest. The pain that arises can be quite severe, and is often described as burning or tingling in nature. Patients with chest pain secondary to zoster and no rash may be indistinguishable from those with cardiac chest pain, so it is wise to assume that a cardiac condition may be present and to act accordingly.

Conclusion

   So how can you know when chest pain isn't due to cardiac causes? You can't always know for sure, especially in the prehospital setting. In many cases, further evaluation and specific diagnostic tests will be needed to make a definitive diagnosis, but you can familiarize yourself with some of the more common causes included in the differential diagnosis of chest pain. We have not given an exhaustive list here of all non-cardiac causes of chest pain, but we have discussed some of those EMS providers are likely to encounter. We have provided some tips/guidelines for differentiating the most common causes (both cardiac and non-cardiac) of chest pain in Table 1.

   The take-home message: Keep an open mind about the possibility of non-cardiac causes for chest pain. Be alert for the "red flags" that may indicate a non-cardiac pathology. Thinking about the differential diagnosis of chest pain can be rewarding as a method of developing thought processes that can improve the prehospital provider's skills.

Protocol Change: Yes or No?

Now that we have discussed some of the "other" causes of chest pain, we are, of necessity, drawn to consider whether local EMS protocols should be modified. We can think about this from both the positive and negative sides of the same coin.

On the positive side, some jurisdictions have already changed their protocols so that patients who may be having a true cardiac event will be transported to a cardiac center. The definition of a cardiac center varies, but, as a rule, includes hospitals that have the ability to perform emergent cardiac catheterizations and/or open heart surgical procedures. However, the guidelines relating to which patients to transport there, perhaps bypassing other hospitals, usually includes those who have well-defined acute changes on their electrocardiogram (such as ST segment elevations or new-onset left bundle branch block) in association with their clinical symptoms. Those people would most likely benefit from early intervention, and they may be easier to identify in the field because of the ECG changes.

A problem with this approach involves treatment of patients in the field by basic EMTs rather than paramedic level providers, since it is not generally within their scope of practice to obtain and interpret 12-lead ECGs. This is not an insurmountable obstacle, however. In some areas of the country, ECGs can be obtained in the field and sent to a medical control facility, either by telemetry or by telephone, for interpretation. Medical control then decides where to transport the patient and instructs the crew.

The negative position is perhaps the more complicated one. This involves patients with chest pain who are actually suffering from some other, non-cardiac condition. It is almost always more difficult to distinguish these patients from those with apparent ECG changes, since there is no single "marker" that will reveal the true cause of the symptoms. This difficulty is not only true in the field, but also in the ED. It is this difficulty that leads to many patients with chest pain and normal or non-diagnostic ECGs being admitted to monitored beds within the hospital. Certainly this is a waste of resources, both in physical space and equipment, as well as in the need for additional skilled personnel to care for the patients. In reality, many of the patients in this situation who are admitted to the hospital are discharged 1-2 days later with a diagnosis other than ACS.

In the end, it remains a regional issue of how to approach and evaluate patients with the chief complaint of chest pain, and how to make decisions that may be potentially lifesaving regarding the correct disposition of the patient. Regional control is a superior option over more diffuse decision-making bodies, since the regional EMS authorities have a far better handle on the resources available in their geographic area and the skills and weaknesses of their providers at any given time. They are also more aware of the numbers of such patients treated each year and the numbers of prehospital providers at all levels who are trained within the region.

   Bernard Beckerman, MD, is an associate professor in the Physician Assistant Program at York College-City University of New York, deputy chief for medical affairs for Plainview Fire Department, Plainview, New York College, and is a long-time member of EMS World Magazine's editorial advisory board.

   Linda Jo Dill, MS, RPA-C, PhD, is an associate professor and academic coordinator in the Physician Assistant Program at York College-City University of New York.