By Dr. Anthony C. Pearson, MD, FACC
Poor R-wave progression (PRWP) is a common ECG finding that occurs when the expected normal increase in R-wave amplitude does not appear in successive 12-lead precordial leads. Although studies show that PRWP is frequently reported by both cardiologists and computer-aided ECG interpretations, its significance is questionable, and faulty ECG lead placement likely contributes substantially to ECG misdiagnosis, unnecessary testing, and extraneous health costs.
Definition of PRWP
Despite its high prevalence, the precise definition, diagnostic, and prognostic implications of PRWP are unclear.
The term PRWP arose as cardiologists attempted to describe the absence of the typical precordial R-wave height increase from V2 to V3 and the expectation of an R-wave height of at least 3 mm in V3. Definitions vary from study to study and likely from one computerized ECG analysis system to another. More recent studies use multiple criteria and typically exclude ECGs with features of LVH. The GE Marquette computerized ECG analysis system excludes LVH and uses either of the following combinations:
- RV3 or RV4 <2 mm plus a decrease in RV2 to RV3 or RV3 to RV4
- RV3 <1 mm plus <0.25 mm increase from RV2 to RV3
Some studies have also included reverse R-wave progression as a type of PRWP. Reverse R-wave progression is characterized by decreasing R-wave amplitude such that the R wave in lead V4 is smaller than the R wave in V3, or the R wave in V3 is smaller than the R wave in V2, or the R wave in V2 is smaller than the R wave in V1 (or any combination of these), provided that the R-wave amplitude in V3 was 3 mm or less.
It should be noted that reverse R-wave progression is often created by technician error when leads V2 and V3 or V3 and V4 are mistakenly reversed.
Prevalence of PRWP
The prevalence of PRWP varies depending on the population studied and the criteria utilized. In a series of 19,734 ECGs performed for a life insurance company and documented in the Journal of Insurance Medicine, PRWP was the sixth most common abnormal ECG pattern.1 A survey of the literature published in Cureus in 2020 concluded that the average incidence varies from 11.37% to 16.08% depending on the population and criteria being observed.2
Causes of PRWP
ECGs that meet the criteria for PRWP are often reported out as showing "anterior myocardial infarction" (AMI). Typically, such statements are made with qualifying language like "cannot rule out," "possible," or "probable." While PRWP is noted in the setting of AMI, it may also be caused by left or right ventricular hypertrophy or a variant of normal with diminished anterior forces, according to an Archives of Internal Medicine review.3
A study published in the American Heart Journal looked at the value of several ECG criteria for the diagnosis of AMI using SPECT scintigraphy as the gold standard in a population undergoing clinical stress testing. Depending on the PRWP criteria utilized, the prevalence of PRWP was 15% to 42%. Prevalence of scintigraphy-confirmed AMI in those displaying PRWP ranged from 2% to 9% depending on the criteria.4
The authors asserted that "conclusions about the presence of AMI solely on the basis of PRWP have little usefulness."
Lead Misplacement
A study in the Journal of Electrocardiology examined the technical and constitutional factors contributing to PRWP in normal subjects. The authors identified 100 individuals at the time of a normal cardiac catheterization and found that eight of them had PRWP that was not related to any of the factors measured, including age, sex, BSA, blood pressure, and thoracic skeletal abnormalities. They prospectively analyzed the effect of precordial lead misplacement and respiratory variation in 68 hospitalized patients and were able to create false positive PRWP by superior displacement from the proper precordial lead position.5
A study in the Journal of Clinical Practice found that precordial leads V1 and V2 were often placed in the second intercostal space by physicians. The correct position of V1 in the fourth right intercostal space was identified by 90% of ECG technicians and 49% of nurses but only 31% of non-cardiologist physicians. Unexpectedly, cardiologists did most poorly, positioning the electrode properly only 16% of the time.6
Luckily, another study in the Journal of Electrocardiology demonstrated that poor lead placement could be corrected. One-hundred staff members, including doctors, nurses, and ECG technicians, were chosen at random to place sticker dots on a mannequin for assessment. Prior to an educational intervention, only 34% of lead placements across the three groups were correct, with the best performance coming from ECG technicians, who achieved perfect lead placement 55% of the time. The most common error was placement of leads V1 and V2 superiorly, an error known to create PRWP. Following an educational intervention, the proportion that achieved correct placement of any lead rose significantly, from 34% to 83%.7
To learn more about the power of the ECG in today's clinical landscape, browse our Diagnostic ECG Clinical Insights Center.
Healthcare Costs of PRWP
False positive diagnoses of AMI based on PRWP from faulty lead placement can lead to unnecessary testing, including stress testing and cardiac catheterizations. In addition to the adverse consequences of such downstream testing, ECG misdiagnosis can also result in additional costs to the healthcare system.
The same above-mentioned article published in Cureus that estimated the incidence of PRWP also analyzed these costs. Researchers retrospectively analyzed 9,424 ECGs with AMI, LVH, LAFB, and LBBB. Ventricular pacing and low voltage were excluded, as these are known to cause PRWP, leaving 6,808 ECGs for analysis.
Of those ECGs, 7.3% met criteria for PRWP, and in 10.8% of cases, precordial lead misplacement was suspected, creating an abnormal pattern suggestive of myocardial infarction and raising suspicion of CAD. Projecting the downstream testing for CAD assessment, the authors estimated the cost to the Centers for Medicare & Medicaid Services of ECG lead mispositioning at $3.2 billion.
How Cardiologists Should Think about PRWP
Given that PRWP has little or no clinical significance and can easily be created by common errors in ECG lead placement, ECG readers are probably best served by eliminating this term from their reporting vocabulary. If reading cardiologists do not eliminate the computer-generated qualifier, "cannot rule out AMI," when PRWP is present, they may generate more harm than good with their interpretations, adding to healthcare costs, anxiety in the worried well, and the potential adverse consequences of downstream testing.
References:
1. Poor R-Wave Progression. Journal of Insurance Medicine. https://www.aaimedicine.org/journal-of-insurance-medicine/jim/2005/037-01-0058.pdf. Last accessed August 2021.
2. Precordial ECG Lead Mispositioning: Its Incidence and Estimated Cost to Healthcare. Cureus. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7343296/. Last accessed August 2021.
3. ECG poor R-wave progression: review and synthesis. Archives of Internal Medicine. https://europepmc.org/article/med/6212033 Last accessed August 2021.
4. Electrocardiographic poor R-wave progression: analysis of multiple criteria reveals little usefulness. American Heart Journal. https://www.sciencedirect.com/science/article/abs/pii/S000287030400095X Last accessed August 2021.
5. Electrocardiographic poor R wave progression III: The normal variant. Journal of Electrocardiology. https://pubmed.ncbi.nlm.nih.gov/7365354/ Last accessed August 2021.
6. Accuracy in ECG lead placement among technicians, nurses, general physicians and cardiologists. The International Journal of Clinical Practice. https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1742-1241.2007.01390..x Last accessed August 2021.
7. Accuracy in precordial ECG lead placement: Improving performance through a peer-led educational intervention. Journal of Electrocardiology. https://www.sciencedirect.com/science/article/abs/pii/S0022073617301218?via%3Dihub. Last accessed August 2021.
Dr. Anthony C. Pearson, MD, FACC is a Professor of Medicine at the St. Louis University School of Medicine Division of Cardiology and specializes in general and noninvasive cardiology.
The opinions, beliefs, and viewpoints expressed in this article are solely those of the author and do not necessarily reflect the opinions, beliefs, and viewpoints of GE Healthcare. The author is a paid consultant for GE Healthcare and was compensated for creation of this article.
