How do you interpret a paced rhythm when comparing a narrow QRS vs a wide QRS in dual vs single chamber pacing?

How do you interpret a paced rhythm when comparing a narrow QRS vs a wide QRS in dual vs single chamber pacing?

• A. Narrow QRS suggests ventricular pacing; wide QRS indicates atrial pacing with intact conduction.
• B. Narrow QRS suggests atrial pacing with intact conduction; wide QRS with pacing spike indicates ventricular pacing or loss of capture; check device mode.
• C. Both narrow and wide QRS indicate lead dislodgement.
• D. Narrow QRS indicates pacing failure; wide QRS indicates accurate capture.

Answer: (B)