We can all recall learning about the NYHA classification, and being taught to ask about our CHF ” greatest hits”: orthopnea, dyspnea on exertion, number of pillows (my favorite question), worsening edema, etc., but how does this stack up in the literature?
Luckily, a well titled paper called “Does This Dyspneic Patient in the Emergency Department Have Congestive Heart Failure?” (Wang et. al, 2005) answered this question.
In essence, this paper demonstrated that a lot of the symptoms, listed above, that we associate with CHF actually have somewhat meager likelihood ratios for diagnosing CHF. They are still important to ask because they inform our overall clinical picture of the patient. However, it is important to delve into the strengths and limitations of some of these findings. So let’s dive in…
The Best Predictors for CHF diagnosis on H+P (based on LR>4.0)
- Third Heart sound, S3 (LR 11). –UWorld loves this question because it is the physical exam finding most associated with diagnosis of CHF
- Prior History of CHF (LR 5.8)–Without a doubt, the best answer in any diagnosis is that they already have it.
- Abdominojugular Reflux (LR 6.4) or JVD (LR 5.1). –easily one of the coolest findings when visible but often concealed by some extra habitus in that area
- Initial Clinical Judgment (LR 4.4)
This in comparison to our CHF “greatest hits” that range in LR 1.3-2.8
- Rales (LR 2.8)
- Paroxysmal Nocturnal dyspnea (LR 2.6)
- Lower-extremity Edema (LR 2.3)
- Orthopnea (LR 2.2)
- Dyspnea on Exertion (LR 1.3)
Now, what part of our workup is most important at making this diagnosis?
Chest Xray is Great!
– Pulmonary venous congestion (LR 12.0)
– Interstitial edema (LR 12.0)
– Alveolar Edema (6.0)
– Cardiomegaly (3.3)
– Pleural Effusions (LR 3.2)
High BNP increases likelihood of CHF
– BNP >250 (LR 4.6)
– BNP >200 (LR 3.7)
– BNP >150 (LR 3.1)
– BNP >100 (LR 2.7)
Low BNP decreases likelihood of CHF
– BNP<100 (LR 0.06)
In the ED, the patient with dyspnea on exertion is omnipresent, and this presenting complaint has a wide differential with CHF being one of the more common causes we encounter. From the article, we can see that history of CHF, S3, JVD, and abdominojugular reflux have the highest likelihood ratios (LR>5) for diagnosing CHF, while rales, PND, lower extremity edema, orthopnea, and DOE (LR 1.3-2.8) are associated with somewhat lower likelihood ratios. However, all of these findings taken together inform our initial clinical judgment, and this initial judgment has been shown to be a strong predictor of CHF (LR 4.4).
Furthermore, our workup of the patient can point us towards the correct diagnosis. This workup is likely to include a CBC, CMP, troponin, BNP, VBG lactate, CXR, and EKG. Chest Xray was associated with the highest likelihood ratios, while BNP had great utility in ruling in (BNP>100) and ruling out (BNP<100) a CHF diagnosis. However, when evaluating BNP, it is important to keep in the back of your mind other causes of an elevated BNP including CKD, liver disease (ascites), PE, MI, stroke, SAH, and sepsis (by no means an exhaustive list), as well as causes of a falsely lowered BNP as seen in obesity.
1: Wang, C. (2005). Does This Dyspneic Patient in the Emergency Department Have Congestive Heart Failure?. JAMA, 294(15), p.1944.
Pictured above and in the featured image is Dr. William Harvey, who is credited as the first physician to describe in detail the systemic circulation. This work was called De Motu Cordis (On the Motion of the Heart and Blood). He is the one to blame for all the discoveries and mechanisms that were uncovered thereafter. He is also credited for having one of the best “Letters of Recommendation” upon graduation from med school: “[He] conducted himself so wonderfully well in the examination and had shown such skill, memory and learning that he had far surpassed even the great hopes which his examiners had formed of him.” In addition to describing circulation, William also spent time as as an “examiner” of witchcraft cases. William was a known sceptic of witchcraft and was involved in the acquittal of several persons accused during his lifetime. You have to hand it to a guy who had time to describe the entire cardiovascular system in detail and disprove witchcraft all in one career.