Why was the myocardial infarction in my postop patient silent?

Myocardial infarction (MI) in postop patients is in fact usually silent (1,2) but what is less clear is how myocardial ischemia can occur without any symptoms.

Although use of analgesics and narcotics postop may dampen or mask chest pain or other symptoms associated with MI, other factors are also likely to play an important role, such as decreased sensitivity to painful stimuli, autonomic neuropathy (eg, in diabetes mellitus), and higher pain threshold among some patients (3).

Additional factors associated with silent MIs include cerebral cortical dysfunction since frontal cortical activation appears to be necessary to experience cardiac pain. Mental stress is also a frequent trigger for asymptomatic myocardial ischemia, infarction and sudden cardiac death (4).  High levels of beta-endorphin, an endogenous opiate, may also play a role (5).

 
Perhaps the most intriguing explanation for lack of symptoms is the observation that the levels of anti-inflammatory cytokines (interleukin-4 and -10)—which block pain transmission pathways and increase the threshold for nerve activation—seem to be increased in patients with silent myocardial ischemia (6).  Even more relevant to our postop patient is the finding that interleukin-10 production increases during and after major abdominal surgery and correlates with the amount of intraoperative blood loss (7). 

No wonder MIs in postop patients are often silent!

References
1. Devereaux PJ, Xavier D, Pogue J, et al. Characteristics nd short-term prognosis of perioperative myocardial infarction in patients undergoing noncardiac surgery: a cohort study. Ann Intern Med 2011;154:523-8. https://annals.org/aim/article-abstract/746934/characteristics-short-term-prognosis-perioperative-myocardial-infarction-patients-undergoing-noncardiac 
2. Badner NH, Knill RL, Brown JE, et al. Myocardial infarction after noncardiac surgery. Anesthesiology 1998;88:572-78. http://anesthesiology.pubs.asahq.org/article.aspx?articleid=1948483
3. Ahmed AH, Shankar KJ, Eftekhari H, et al. Silent myocardial ischemia:current perspectives and future directions. Exp Clin Cardiol 2007;12:189-96. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2359606/ 
4. Gullette EC, Blumenthal JA, Babyak M, et al. Effects of mental stress on myocardial ischemia during daily life. JAMA 1997;277:1521-6. https://jama.jamanetwork.com/journals/jama/articlepdf/416233/jama_277_19_029.pdf
5. Hikita H, Kurita A, Takase B, et al. Re-examination of the roles of beta-endorphin and cardiac autonomic function in exercise-induced silent myocardial ischemia. Ann Noninvasive Electrocardiol 1997;2:319-25. https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1542-474X.1997.tb00195.x
6. Mazzone A, Cusa C, Mazzucchelli I, et al. Increased production of inflammatory cytokines in patients with silent myocardial ischemia. J Am Coll Cardiol 2001;38:1895-901. https://www.ncbi.nlm.nih.gov/pubmed/11738291
7. Kato M, Honda I, Suzuki H, et al. Interleukin-10 production during and after upper abdominal surgery. J Clin Anesth 1998;10:184-8. https://www.ncbi.nlm.nih.gov/pubmed/9603586 

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Why was the myocardial infarction in my postop patient silent?

My patient with angina symptoms also complains of neck pain with left arm numbness. Could they be related?

Short answer, yes! Anterior chest pain associated with cervical intervertebral disk disease, ossified posterior longitudinal ligament or other spinal disorders is sometimes referred to as “cervical angina” (CA) or “pseudoangina” and is an often overlooked source of non-cardiac chest pain. 1-5

Although its exact prevalence is unknown, 1.4% to 16% of patients undergoing cervical disk surgery may have symptoms of CA. 1 Conversely, 1 study reported 5% of patients with angina pectoris having cervical nerve root pathology.5 Many patients describe their chest pain as “pressure” or crushing in quality mimicking typical cardiac ischemia chest pain, often resulting in extensive cardiac workup.  To add to the confusion, some patients even respond to nitroglycerin! One-half of patients also experience autonomic symptoms such as dyspnea, vertigo, nausea, diaphoresis, pallor, fatigue, and diploplia.1

Certain clues in the patient’s presentation should help us seriously consider the possibility of CA: 1-3

  • History of cervical radiculopathy eg, subjective upper extremity weakness or sensory changes, occipital headache or neck pain
  • Pain induced by cervical range of motion or movement of upper extremity
  • History of cervical injury or recent manual labor (eg, lifting, pulling or pushing)
  • Pain lasting greater than 30 min or less than 5 seconds and not relieved by rest
  • Positive Spurling maneuver ie, reproduction of symptoms by rotating the cervical spine toward the symptomatic side while providing a downward compression through the patient’s head

CA is often attributed to cervical nerve root compression, likely mediated by compression of C4-C8 nerve roots which also supply the sensory and motor innervation of the anterior chest wall.

Bonus Pearl: Did you know that experimental stimulation of spinothalamic tract cells in the upper thoracic and lower cervical segments have been shown to reproduce angina pain? 6

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References

  1. Susman WI, Makovitch SA, Merchant SHI, et al. Cervical angina: an overlooked source of noncardiac chest pain. The Neurohospitalist 2015;5:22-27. https://www.ncbi.nlm.nih.gov/pubmed/25553225
  2. Jacobs B. Cervical angina. NY State J Med 1990;90:8-11. https://www.ncbi.nlm.nih.gov/pubmed/2296405
  3. Sheps DS, Creed F, Clouse RE. Chest pain in patients with cardiac and noncardiac disease. Psychosomatic Medicine 66:861-67. https://www.ncbi.nlm.nih.gov/pubmed/15564350
  4. Wells P. Cervical angina. Am Fam Physician 1997;55:2262-4. https://www.ncbi.nlm.nih.gov/pubmed/9149653
  5. Nakajima H, Uchida K, Kobayashi S, et al. Cervical angina: a seemingly still neglected symptom of cervical spine disorder. Spinal Cord 2006;44:509-513. https://www.ncbi.nlm.nih.gov/pubmed/16331305
  6.  Cheshire WP. Spinal cord infarction mimicking angina pectoris. Mayo Clin Proc 2000;75:1197-99. https://www.ncbi.nlm.nih.gov/pubmed/11075751

 

My patient with angina symptoms also complains of neck pain with left arm numbness. Could they be related?

My patient with low back pain was just diagnosed with a lumbar spinal epidural abscess. Should I order an MRI of the rest of the spine?

First, look closely for any signs or symptoms which may suggest cord involvement due to spinal epidural abscess (SEA) at other levels of the spine (in this case cervical or thoracic) which would necessitate an urgent MRI. Be particularly on the lookout for new pain (particularly radicular) or paresthesias involving the abdomen, chest or upper extremities (with or without weakness)1.

Otherwise, whether an MRI of the entire spine should be routinely obtained after a diagnosis of SEA in the absence of any suggestive signs or symptoms is less clear, in part related to lack of properly designed studies.1-4

Nevertheless, a retrospective study involving 233 patients with SEA may shed some light on the subject. Based on 22 cases of noncontiguous SEA (9.4% of total), the following independent risk factors were identified3:

  • Delay in presentation (≥1 week of symptoms)
  • Concomitant area of infection outside the spine and paraspinal region
  • ESR > 95 mm/h at presentation

Probability of non-contiguous SEA based on the number of risk factors was as follows:

  • 3 risk factors: 73%
  • 2 risk factors: 13%
  • 1 risk factor: 2%
  • Zero risk factor: 0%

Despite several shortcomings and the need to confirm its findings2,3, this study helps raise awareness of the potential for concurrent but asymptomatic SEA elsewhere in the spine whenever SEA is diagnosed.

 

References

  1. Bond A, Manian FA. Spinal epidural abscess: a review with special emphasis on earlier diagnosis. BioMed Res International 2016;Volume 2016, Article ID 1614328. https://www.hindawi.com/journals/bmri/2016/1614328/
  2. Schoenfeld AJ, Hayward RA. Predicting modeling for epidural abscess: what we can, can’t, and should do about it. Spine J 2015;15:102-104. http://www.sciencedirect.com/science/article/pii/S152994301401554X
  3. Ju KL, Kim SD, Melikian R, et al. Predicting patients with concurrent noncontiguous spinal epidural abscess lesions. Spine J 2015;15:95-101. https://www.ncbi.nlm.nih.gov/pubmed/24953159
  4. Pfister HW, vonRosen F, Yousry T. MRI detection of epidural spinal abscesses at noncontiguous sites. J Neurol 1996;243:315-7. https://www.ncbi.nlm.nih.gov/pubmed/8965103
My patient with low back pain was just diagnosed with a lumbar spinal epidural abscess. Should I order an MRI of the rest of the spine?

When should I consider ordering a coronary CT-angiogram (CCTA) in my patient with chest pain?

In patients at low-to-intermediate risk of coronary artery disease (CAD), CCTA is a viable alternative to functional stress tests and may facilitate triage decisions, as well as reduce the risk of missed myocardial infarctions and length of hospital stay (1,2). Although compared to conventional coronary angiography CCTA has lower specificity (64-90%), it has consistently been shown to have high sensitivity (>95%) and negative predictive values (>95%) for obstructive coronary stenosis, supporting its potential role in “ruling out” significant CAD in low-to-intermediate risk patients (1-2).

A coronary artery calcification (CAC) score is also commonly measured when CCTA is performed; a very high CAC score can interfere with proper interpretation of CCTA.  A negative CCTA combined with a CAC score of zero makes CAD-related chest pain extremely unlikely. The additional prognostic value of CAC score other than zero to CCTA is unclear (2).

References

  1. Budoff MJ, Dowe D, Jollis JG, et al. Diagnostic performance of 64-multidetector row coronary computed tomographic angiography for evaluation of coronary artery stenosis in individuals without known coronary artery disease: results from the prospective multicenter ACCURACY (Assessment by Coronary Computed Tomographic Angiography of Individuals Undergoing Invasive Coronary Angiography) trial. J Am Coll Cardiol. 2008;52(21):1724.
  2. Villines TC,  Hullen EA, Shaw LJ, et al. Prevalence and severity of coronary artery disease and adverse events among symptomatic patients with coronary artery calcification scores of zero undergoing coronary computed tomography angiography results from the CONFIRM (Coronary CT Angiography Evaluation for Clinical Outcomes: an International Multicenter) registry. J Am Coll Cardiol 2011;58:2533-2540.

 

Contributed by Stephanie Meller, MD, Boston, MA.

 

When should I consider ordering a coronary CT-angiogram (CCTA) in my patient with chest pain?