As a medical professional with expertise in cardiology, I can explain that poor R wave progression in an electrocardiogram (ECG) can be caused by several factors. Normally, as you move across the precordial leads (V1 to V6), the R wave should increase in amplitude, reflecting the left ventricular depolarization wave as it spreads across the heart. When this progression is not observed, it may indicate an underlying issue. 1. Anterior Myocardial Infarction (MI): An old anterior MI can indeed cause poor R wave progression. The infarction can damage the heart muscle, leading to a disruption in the normal electrical conduction and thus affecting the expected increase in the R wave. 2. Bundle Branch Block (BBB): A block in one of the bundle branches of the electrical conduction system can alter the normal sequence of ventricular depolarization, which can result in an abnormal R wave progression. 3. Cardiomyopathy: Conditions such as hypertrophic or dilated cardiomyopathy can cause changes in the heart's structure and function, which may lead to poor R wave progression. 4. Pericarditis: Inflammation of the pericardium can affect the electrical activity of the heart and lead to changes in the ECG, including poor R wave progression. 5. Pulmonary Embolism (PE): A PE can cause strain on the right side of the heart, which may be reflected in the ECG as changes to the R wave. 6. Lead Misplacement or Technical Issues: Sometimes, the issue may be as simple as a misplaced lead or technical error in recording the ECG. It's important to consider the patient's clinical history, symptoms, and other diagnostic findings to determine the cause of poor R wave progression. A thorough evaluation by a healthcare professional is necessary for an accurate diagnosis. read more >>

In lead V1, the R wave should be small. The R wave becomes larger throughout the precordial leads, to the point where the R wave is larger than the S wave in lead V4. The S wave then becomes quite small in lead V6. Note that an old anterior myocardial infarction can cause poor R wave progression.read more >>