What does poor R (rhythm) wave progression signify in an electrocardiogram (ECG)?

From the Guidelines

Poor R wave progression is a significant finding on an electrocardiogram (ECG) that may indicate several cardiac conditions, including anterior myocardial infarction, left ventricular hypertrophy, or improper lead placement, and requires further cardiac evaluation to determine the underlying cause. This finding refers to the absence or diminishment of the normal increase in R wave amplitude from lead V1 to V6 across the precordial leads. Normally, the R wave should progressively increase in size while the S wave decreases when moving from the right side of the chest (V1) to the left side (V6) 1.

Causes of Poor R Wave Progression

• Anterior myocardial infarction (heart attack), where scar tissue replaces normal heart muscle
• Left ventricular hypertrophy
• Improper lead placement during ECG recording, such as superior misplacement of V1 and V2 in the second or third intercostal space, which can result in reduction of initial R-wave amplitude in these leads, approximating 0.1 mV per interspace 1
• Anatomical variations in chest wall structure, such as low diaphragm position in obstructive pulmonary disease, which can cause V3 and V4 to be located above the ventricular boundaries and record negative deflections that simulate anterior infarction 1

Clinical Significance

Poor R wave progression is significant because it may represent loss of viable heart muscle in the anterior wall of the left ventricle. If poor R wave progression is identified on an ECG, further cardiac evaluation is typically recommended, which may include echocardiography, stress testing, or cardiac MRI to determine the underlying cause 1.

Importance of Proper Lead Placement

Proper lead placement is crucial in avoiding false diagnoses, as misplacement of precordial electrodes can result in profound alterations in waveforms, leading to erroneous signs of anterior infarction or poor R wave progression 1. It's essential to interpret this finding in the context of the patient's clinical presentation, as poor R wave progression alone is not diagnostic of any specific condition but serves as a clue for further investigation.

From the Research

Definition and Causes of Poor R Wave Progression

• Poor R-wave progression (PRWP) is a common clinical finding on the standard 12-lead electrocardiogram (ECG) 2
• PRWP has been associated with several causes, including anterior myocardial infarction (AMI), left ventricular hypertrophy, right ventricular hypertrophy, and a variant of normal with diminished anterior forces 3

Diagnostic Significance of Poor R Wave Progression

• The diagnostic significance of PRWP is unclear, with some studies suggesting it may be associated with adverse prognosis in the general population and with sudden cardiac death in subjects with coronary artery disease 2
• However, other studies have found that PRWP has little usefulness in diagnosing anterior myocardial infarction, with only a small percentage of patients meeting PRWP criteria actually having anterior MI 4
• A scoping review found that the quantity and quality of evidence supporting the association between PRWP and coronary disease is limited, with no high-quality accuracy studies identified and existing research suffering from methodological issues 5

Association with Coronary Artery Disease

• PRWP has been associated with coronary artery disease, with one study finding that PRWP was associated with a stronger association with cardiac mortality in the subgroup with CAD than in the subgroup without CAD 2
• However, another study found that PRWP was not a reliable indicator of coronary artery disease, with a trend toward a less severe degree of contraction abnormality on contrast ventriculography in patients with PRWP or RRWP compared to those with Q wave anterior myocardial infarctions 6

Clinical Interpretation

• The lack of solid evidence for PRWP as a diagnostic marker for acute and chronic coronary artery disease necessitates caution in clinical interpretation 5
• Clinicians should be aware of the limitations of PRWP in diagnosing anterior myocardial infarction and consider other diagnostic criteria and tests, such as nuclear stress tests, to confirm the presence of coronary artery disease 4