ECG Interpretation

Measured parameters (from the printed header)

Visual reading of the tracing

• The rhythm strip (lead II) shows a regular, narrow P wave preceding every QRS at ~65/min - sinus rhythm.
• Every QRS across all 12 leads is visibly wide and slurred, consistent with the machine's 148 ms measurement.
• This combination of a very wide QRS + marked right axis deviation, with a normal PR interval (so this is not WPW, which would show a short PR with a delta wave), is the classic electrical signature of right bundle branch block (RBBB). Isolated RBBB alone doesn't usually push the axis this far to the right (+147°) - right axis deviation of this degree occurring together with RBBB is described in the literature as RBBB + left posterior fascicular block, i.e., a bifascicular block pattern (Ganong's Review of Medical Physiology; Goldman-Cecil Medicine, "Intraventricular blocks").
• The T axis being discordant (-18°, opposite direction from the QRS) is an expected secondary repolarization change that accompanies a wide-QRS conduction block rather than necessarily indicating primary ischemia.
• Regarding the "prolonged" QTc: because QT includes the QRS duration, a QRS this wide will mechanically prolong the QT/QTc reading. Subtracting QRS from QT gives a JT interval of 448 - 148 = 300 ms, which is not clearly abnormal - so the QTc prolongation here is largely an artifact of the wide QRS rather than a separate repolarization abnormality.

Clinical significance

• They reflect diffuse conduction system disease and carry a risk of progression to higher-grade AV block.
• If this patient has had syncope, presyncope, or unexplained dizziness, current evidence (a randomized trial cited in Goldman-Cecil Medicine, Sheldon et al., JACC Clin Electrophysiol 2022;8:239-248) supports pacemaker evaluation over implantable loop recorder monitoring in syncope with bifascicular block.
• A wide QRS of this degree in an acute-care setting should also prompt a quick check for hyperkalemia or other toxic/metabolic causes of QRS widening, and a search for structural heart disease (echocardiogram), since these are common causes of new intraventricular conduction delay.

Caveat

• The abnormalities I found were conduction-related (QRS 148 ms, right axis deviation 147°, pattern of right bundle branch block ± left posterior fascicular block), not ischemic. I didn't see ST-segment elevation, ST depression, or pathological Q waves in the leads.
• Importantly, RBBB does not mask ST/Q-wave changes of infarction the way LBBB does. Per Harrison's and Frameworks for Internal Medicine, it's specifically left BBB (and ventricular paced rhythms/WPW) that hide or mimic ischemic ST changes - RBBB leaves the ST segments and Q waves largely interpretable, so if there were an acute MI, it would generally still show through.
• The T-wave axis discordance (-18°) I flagged is the expected secondary repolarization change that simply accompanies a wide QRS from bundle branch block - not itself a marker of ischemia.