Thursday, April 19, 2012

Shortness of breath on exertion and pulmonary embolism - Thursday April 19, 2012

Thank you to team 5 for bringing an interesting case.

Today, we discussed a case of a man with significant previous coronary artery disease treated with coronary artery bypass graft surgery and multiple stenting.  He has known LVEF of 20-39%.  He presented to the Emergency Department with shortness of breath on exertion.

We discussed the pertinent history features when someone presents with previous coronary artery disease.  They include previous infarctions, interventions (surgery, interventional, or medical), presence of heart failure, and functional status (CCS class).  We also discussed the reason for dual anti-platelet therapy post-stenting and the minimum duration required for this therapy.  We discussed some of the typical medical management for patients with coronary artery disease (anti-platelet, beta-blocker, ACE-inhibitor, statin).  We compared this with the medications that our patient was on.  We then generated a list of differential diagnoses for our patient, which included heart failure (exacerbation), pulmonary embolism, pneumonia, new ischemia, bleeding, and less likely obstructive lung disease, or malignancy.  We also discussed the etiologies of heart failure and its triggers.

We looked at his CXR, which showed poor inspiration (we discussed how to determine this by counting ribs), with a right-sided consolidation.  The CT thorax showed pulmonary embolism (likely not acute) and right-sided consolidation.  Five months ago, this patient had a “high probability” V/Q scan followed by a negative CT PE study at a different hospital.  The team started this patient on anticoagulation.

We then discussed the etiology of his PE.  We discussed the usual risk factors for PE such as trauma, surgery, malignancy, immobility (including travel), and thrombophilia.  We did not have enough time to discuss this thoroughly, but we did note that this patient developed new-onset microcytic anemia and that a work-up is necessary.

We did not have time to discuss diagnosis of PE with the different modalities.  There was a systematic review on the different modalities used to diagnose PE in the BMJ in 2005 [331(7511):259], linked here.  Our patient had a “high probability” V/Q scan 5 months ago at a different hospital.  The PIOPED study (JAMA 1990, linked here) studied the diagnostic accuracy of V/Q scan.  In that study, 88% of patients with “high probability” V/Q scan had PE on angiogram (gold standard for that study).

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