Chest pain overview

# Overview
After  injuries, chest  pain  is  the  second  most common  cause of seeking medical attention in emergency  department  (ED) in the United  States  and responsible  for >6.5 million visits, which is 4.7% of all ED  visits. Chest pain also is the cause of nearly 4 million outpatient visits every year in the United States. Chest pain remains a diagnostic challenge in the ED and outpatiet setting and needs thorough  clinical  evaluation. Causes of chest pain include noncardiac,and cardiac in which noncardiac chest pain is responsible for  more than half of ED visits and only 5.1% will have an acute coronary syndrome. Coronary artery  disease (CAD) is the leading cause of death for men and women. Distinguishing between serious and benign causes of  chest pain is important. Chest pain is the most symptom of CAD in both men and women.

# Historical Perspective
The first recorded description of chest pain was given by Benivieni, a Florentine physician in the early 1500s. The first concise account of angina pectoris was given by the then Earl of Clarendon when he described his father's illness. Angina pectoris was described by a medical practitioner when Dr. William Heberden read his paper to the College of Physicians in London on 21 July 1768.

# Classification
Chest pain traditionally has been classified into typical and atypical types. Chest pain that is more likely associated with ischemia includes substernal chest discomfort aggravated by exertion or emotional stress and relieved by rest or nitroglycerin. Ischemic chest discomfort  can be described based on quality, location, radiation, and provoking and relieving factors. Using the term of atypical chest pain is problematic. Although the term of atypical chest pain was intended to describe angina without typical chest symptoms, it is more often used to consider that the symptom is noncardiac in origin. Then, it is discouraged using the term of atypical chest pain. Notably, chest pain is a broadly term to define referred pain in the shoulders, arms, jaw, neck, and upper abdomen. So, using the terms of cardiac, possible cardiac, and noncardiac are encouraged to describe the suspected causes of chest pain.

# Pathophysiology
The cardiovascular system, respiratory system, part of the gastrointestinal system, and the great vessels give off afferent visceral input via common thoracic autonomic ganglia. Painful stimuli in any of the aforementioned systems are usually sensed as originating from the chest. However, due to the fact that afferent nerve fibers overlap in the dorsal ganglia, pain in the thorax may be experienced at any point between the umbilicus and the ear, as well as in the upper limbs.

# Causes
There are many organ systems, that when affected, can lead to the symptoms of chest pain.The most common organs involved are the heart, lungs, and the digestive system. Psychiatric disorders, can also lead to the perception of chest pain. The most important facet of diagnosis is distinguishing the life-threatening causes of chest pain, to the more benign causes. Life-threatening causes of chest pain include myocardial infarction, aortic dissection, pulmonary embolism, tension pneumothorax, and esophageal rupture. Other common causes of chest pain include GERD, chest wall tenderness, achalasia, pneumonia, and anxiety.

# Differentiating Chest pain from Other Diseases
There are several life-threatening causes of chest pain which need to be evaluated for first, which include; myocardial infarction, aortic dissection, esophageal rupture, pulmonary embolism, and tension pneumothorax. The other possible causes of chest pain can be evaluated for by carefully assessing the nature of the pain, and obtaining a thorough patient history.

# Epidemiology and Demographics
There is a significant difference in the epidemiology of chest pain in the outpatient and emergency settings. The incidence of chest pain is approximately 1,500 per 100,000 individuals worldwide. According to a study conducted in Belgium, the prevalence of chest pain is approximately 2000-5000 per 100,000 individuals worldwide. The incidence of patients presenting with chest pain increases with age and men are more likely to present with chest pain than women.

# Risk Factors
Common risk factors in the development of chest pain may be associated with the cardiac, respiratory, or gastrointestinal systems. Other risk factors include smoking, obesity, drug abuse, and psychiatric disorders.

# Screening
There is insufficient evidence to recommend routine screening for chest pain

# Natural History, Complications, and Prognosis
Angina pectoris is defined as a retrosternal chest discomfort that increases gradually in intensity (over several minutes). Percipitant factors are physical or emotional stress. In ACS, chest pain may occur during rest. Chest pain is characterized by radiation (left arm, neck, jaw) and its associated symptoms (dyspnea, nausea, lightheadedness). When actively treated or spontaneously resolving, it disappears over a few minutes. Relief with nitroglycerin is not necessarily a diagnostic criterion of myocardial ischemia, especially because other causes such as esophageal spasm may have respons to nitroglycerin. Associated symptoms such as shortness of breath, nausea or vomiting, lightheadedness, confusion, presyncope or syncope, or vague abdominal symptoms are more frequently seen among patients with diabetes, women, and the elderly. A detailed assessment of cardiovascular risk factors, review of systems, past medical history, and family and social history should be done in patients with chest pain. It is pivotal to identify and triage the patients presented with chest pain within 10 minutes of arrival to the hospital. Patients diagnosed with STEMI should be scheduled for primary PCI. Early recognition of STEMI may improve outcomes. Stable angina and non-cardiac chest pain should be evaluated in outpaient setting.
Common complications of chest pain include arrythmia, heart failure and Death. Depending on the etiology at the time of presentation, the prognosis may vary. However, the prognosis is generally regarded as good.

# Chest Pain in Pregnancy
Causes of chest pain in pregnancy are similar to those in the general population. Acute life-threatening causes include myocardial infarction, aortic dissection, tension pneumothorax, as well as thromboembolic diseases that are more common in pregnancy such as pulmonary embolism and amniotic fluid embolism. Occasionally, chest pain in pregnant women is caused by physiological changes in pregnancy, namely chest expansion and breast tenderness.

# Diagnosis

## Diagnostic Study of Choice
Chest pain or chest pain equivalent may be referred as chest pain. Diagnosis of nontraumatic chest pain is frequent challenge for physicians. Initial evaluation is considered for life-threatening conditions such as ACS, aortic dissection, and pulmonary embolism , as well as nonvascular syndromes (eg, esophageal rupture, tension pneumothorax). So, therapy for those with less critical illnesses is reasonable. Although there are several life-threatening causes, chest pain usually reflects a more benign condition. The initial work-up is taking ECG, but exact history, physical examination, biomarkers, and other tests are necessary. There is no association between the intensity of symptoms and seriousness of disease and general similarity of symptoms among different causes of chest pain. A comprehensive history with all characteristics of chest pain including nature; 2) onset and duration, 3) location and radiation, 4) precipitating factors, 5) relieving factors, and 6) associated symptoms should be obtained to identify the underlying causes of chest pain.

## History and Symptoms
The patient's history must be thoroughly investigated to exclude the life-threatening causes of chest pain, such as the cardiovascular ones: acute coronary syndrome, aortic dissection, pulmonary embolism but also the non-cardiac such as tension pneumothorax and esophageal rupture. Chest pain in  myocardial ischemia presented as deep, difficult to localization, and diffuse. Point tenderness is less likely to be symptom of myocardial ischemia. Chest pain characterized by duration, provoking factors, relieving factors, age, cardiac risk factors. Patient history is the most important basis of defining myocardial ischemia. Because of complexity of cardiac symptoms and variable expression of chest pain, ischemic chest pain may be present as non-cardiac chest pain.Characteristic of chest pain with high likelihood of myocardial ischemia including: central, pressure, squeezing, gripping, heaviness, tighness, exertional, stress related, retrosternal, left-sided, dull, aching, Characteristic of chest pain with less likelihood of myocardial ischemia include right-sided, tearing, ripping, burning, sharp, fleeting, shifting, pleuritic, positional.

## Physical Examination
Physical examination should focus on evaluating for the life-threatening causes of chest pain first. A complete physical exam should be done, which includes a thorough cardiac, lung, and abdominal exam.

## Laboratory Findings
Serial troponins and CK-MB should be ordered. Additional laboratory tests include serum electrolytes, a complete blood count, renal function tests, and liver function tests.

## Electrocardiogram
The key findings to look for on an ECG is the ST elevation which is characteristic of myocardial infarction. However, The major challenge is the differential between NSTE-ACS and non-cardiac chest pain. Diffuse ST elevation may point to the diagnosis of pericarditis. A serial ECG should be obtained to evaluate for continued or progression of myocardial injury over time.

## X-ray
Chest X-ray can be useful in the initial evaluation of the patient to ascertain if there is cardiomegaly, pulmonary edema and aortic dissection. CT scanning may be better for visualizing the etiology of chest pain depending on the patient history and their symptoms.

## Echocardiography and Ultrasound
Transthoracic echocardiography (TTE) can be helpful for diagnosis the causes of acute chest pain such as acute aortic dissection, pericardial effusion, stress cardiomyopathy, and hypertrophic cardiomyopathy. In addition, TTE does provide information for patients with acute chest pain and suspected ACS about left and right ventricular function and regional wall motion abnormalities. Stress echocardiography can be used to define ischemia severity and for risk  stratification purposes when 2  contiguous  segments of wall motion abnormalities in coronary  territories are visualized.

## CT scan
Coronary CT angiography (CCTA)  can be helpful to diagnose the extent and severity of nonobstructive and obstructive CAD, as well  as high-risk features of  atherosclerotic  plaque (positive remodeling, low attenuation plaque). Fractional flow reserve  with  CT (FFR-CT) provides additional information about  ischemia related to lesion. Dosimetry is low for CCTA, with effective doses for most patients in the 3 to 5 mSv range.

## MRI
Cardiovascular magnetic resonance imaging  (CMR) is helpful to  accurately determin global  and  regional left  and  right ventricular  function, localized myocardial ischemia  and  infarction,  and  detection of  myocardial  viability. Myocardial   edema and microvascular   obstruction can be determined by CMR to differentiate acute versus chronic MI, as well as other causes  of  acute  chest  pain, including  myocarditis.

## Other Imaging Findings
After ruling out of ACS, rest/stress positron emission tomography  (PET) or single-photon emission computed tomography (SPECT)  myocardial  perfusion  imag-ing (MPI) are helpful for detection of perfusion abnormalities, measures of  left  ventricular  function,  and  high-risk findings, such as transient ischemic dilation. For PET, calculation of myocardial blood flow reserve (MBFR, the ratio of peak hyperemia to resting myocardial blood flow) adds diagnostic and  prognostic  information  over  MPI. Radiation exposure dose is 3 mSv for rest/stress PET with Rb-82 and 10 mSv for Tc-99m SPECT.

## Other Diagnostic Studies
Invasive Coronary Angiography (ICA)  is used to determine the presence and severity of a luminal obstruction of an epicardial coronary artery,  including its location, length, and diameter, as well as coronary blood flow. ICA provides the characterization of high-grade obstructive stenosis and possibility for percutaneous or surgical revascularization. (IFR and FFR) provide  physiologic characteristic of stenosis. Radiation  exposure to  the patient  during an  interventional  procedure varied 4 to 10 mSv and is dependent on procedural duration and complexity. The spatial resolution of ICA is 0.3 mm, so, visualization of  arterioles (diameter  of  0.1  mm)  that  regulate myocardial  blood  flow is impossible. Coronary  vascular  functional  studies  can  be  performed  during  coronary  angiography. In  normal coronary angiography there may be evident  abnormal coronary  vascular  function. Assessment of coronary  microcirculation and  coronary vasomotion by coronary function testing are reasonable.

# Treatment

## Medical Therapy
A correct diagnosis of the underlying cause of the chest pain should be obtained prior to deciding on an appropriate treatment strategy. The most dangerous causes should be evaluated first. If myocardial infarction or ischemia is suspected, the immediate pharmacotherapies including morphine, oxygen, nitrate, aspirin, ACE inhibitors should be initiated.

## Interventions
Common indications of coronary angiography in high risk ACS patients include new  ischemic changes on the ECG, troponin-confirmed acute myocardial   injury, new-onset left ventricular systolic dysfunction  (ejection  fraction <40%), and newly  diagnosed  moderate-severe  ischemia  on  stress  imaging. For high-risk patients presented with documented AMI and normal epicardial coronary arteries on CCTA or invasive coronary angiography, or  nonobstructive  CAD, CMR  and  echocardiography are useful for evaluation of  nonischemic  cardiomyopathy or myocarditis. Among high risk patients, invasive coronary angiography  provides a comprehensive assessment   of   the   extent and severity of obstructive CAD. The  determination  of  the  severity  of  anatomic  CAD  is  critical  to  guide  the  use  of  coronary  revascularization. Approximately  6%  to  15%  of troponin-positive  ACS occurs  in  the  absence  of  obstructive  CAD. Additional  testing  may  be  helpful to determine the strategy of treatment. Evidence  supports  that  CMR can identify wall motion abnormalities and myocardial edema and distinguish infarct-related scar  from  non-CAD  causes  such  as  myocarditis and nonischemic cardiomyopathy. Performing CMR  within  2  weeks  of  ACS, can  be  useful  to  identify  MI  with  nonobstructive  CAD  (MINOCA) from other causes. The  term  obstructive CAD indicates CAD with 50% stenosis. Nonobstructive CAD is used if  CAD <50% stenosis. High risk CAD is defined in the presence of obstructive  stenosis with  left  main  stenosis 50% or anatomically significant 3-vessel disease (70% stenosis).

## Surgery
Common  causes  of  acute  chest pain  in  the  months after CABG include musculoskeletal  pain  from  sternotomy(  the  most  common cause), myocardial  ischemia  from  acute  graft  stenosis or occlusion, pericarditis, pulmonary embolism, sternal  wound infection , nonunion. Post-sternotomy  pain  syndrome is defined as discomfort after thoracic surgery, persisting for at least 2 months, and without  apparent  cause. The incidence  of  post-sternotomy pain syndrome is varied 7%-66% with a higher prevalence in women compared with men within the first 3 months of thoracic surgery but, after 3 months, postoperative sex difference in prevalence was not seen. Causes of Graft  failure  within  the  first  year  post-CABG using saphenous venous grafts are technical  issues, intimal  hyperplasia, thrombosis. Internal mammary artery graft failure within the first-year post-CABG is most commonly attributable to issues with the anastomotic site of the graft. Causes of acute chest pain  several  years  after  CABG include graft stenosis, occlusion or progression of disease in a non-bypassed vessel. One year after  CABG, about 10%-20%  of  saphenous vein grafts fail. By  10  years, about half of saphenous vein grafts  are patent. The  internal  mammary  artery  has  patency  rates  of  90%  to  95%  10  to  15  years  after  CABG. The use of  radial artery grafts for CABG has a higher patency rate at 5 years of follow-up, compared with the use of  saphenous vein grafts.

## Primary Prevention
Make healthy lifestyle choices to prevent chest pain from heart disease: Achieve and maintain normal weight, Control high blood pressure, high cholesterol, and diabetes, avoid cigarette smoking and secondhand smoke, eat a diet low in saturated and hydrogenated fats and cholesterol, and high in starches, fiber, fruits, and vegetables, get at least 30 minutes of moderate intensity exercise on most days of the week, Reduce stress.

## Secondary Prevention
Secondary prevention of chest pain depends on the cause for instance, risk factor modification remains essential part of the secondary prevention strategy in chronic stable angina. Secondary prevention of chest pain caused by GERD is avoiding food  that worsens the symptoms, smoking cessation, weight loss, eating frequent meals, and head raising of the bed while sleeping.