The correct answer is: D. Hyperkalemia

The ECG shows very slow atrial rhythm with P waves (black arrows) morphology suggestive of low ectopic atrial rhythm. Atrial rate is 37 bpm. While some P waves conduct, most of the beats are not proceeded by a P wave and represent junctional escape beats. The QRS complexes are wide with RBBB configuration. Inferior Q waves are present as well as marked increased in anterior forces (increase R waves in V₁ – V₃) indicative of posterolateral as well as inferior infarction of undetermined age. The positive T wave in V₁ and V₂ denotes the age undetermined status.

Patient underwent left heart catherization and was found to have 100% obstruction of the circumflex and obtuse marginal branches as well as 95% stenosis of the right coronary artery.

Widening QRS and junctional escape rhythm as well as peaked and narrow based T waves in the precordial leads (blue stars) are manifestations of mild to moderate hyperkalemia.^1,2 Serum potassium level was 6.4 mEq/L.

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Figure 2

Mattu et al.² reported the electrocardiographic manifestations of hyperkalemia relative to serum potassium level into three levels as: 

1. Mild hyperkalemia 5.5-6.5 mEq/L
       a. Peaked (tented) T-waves with narrow base, best seen in precordial leads
2. Moderate hyperkalemia 6.5-8.0 mEq/L
   1. Peaked T-waves
   2. PR prolongation
   3. Decreased P wave amplitude  
   4. Widening of QRS duration
3. Severe hyperkalemia >8.0 mEq/L
   1. Absence of P-wave
   2. Intraventricular conduction delay, fascicular blocks, BBBs, and QRS axis shift
   3. Progressive widening of QRS resulting in bizarre QRS morphology
   4. Sine-wave pattern, ventricular fibrillation, and asystole

References

1. Littmann L, Gibbs MA. Electrocardiographic manifestations of severe hyperkalemia. J Electrocardiol 2018;51:814-17.
2. Mattu A, Brady WJ, Robinson DA. Electrocardiographic manifestations of hyperkalemia. Am J Emerg Med 2000;18:721-29.