An ECG causing conFusion:
The Challenges of biventricular paced ECG Interpretation
Johanna Bérénice Tonko, MD
Clinical and Research Fellow for interventional Cardiac Electrophysiology and Devices, Department of Cardiology, Guy’s and St.Thomas’ NHS Foundation Trust
Disclosure: The author has no conflict of interests to declare.
A 75-year-old woman with a background of ischaemic heart disease with severely impaired left ventricular function (LVEF 25%), 1st degree AV Block (PR 280ms) and left bundle branch block (QRS 150ms) presented to the emergency department with chest tightness and dyspnoea. She also reported symptoms suggestive of a urinary tract infection and a gastrointestinal bleed in the past few days. The patient was known to have a primary prevention CRTD device inserted 3 years ago. The report of her last routine CRTD check prior to the acute presentation stated a normal device function with stable lead measurements and 99% biventricular pacing.
Upon arrival her heart rate was 56bpm, non-invasive blood pressure 171/95mmHg and 94% oxygen saturation on room air. An urgently performed 12-lead ECG is shown in Figure 1 (note sequential acquisition of limb and precordial leads recording a total of 9 beats, sweep speed 25mm/s). Figure 2 shows the acute ECG in comparison with biventricular paced ECGs prior to the acute admission as well as a historic ECG prior to CRT insertion.
Device settings, comorbidities and medications are detailed below.
CRT-D Device Settings: DDDR mode, base rate 60bpm, paced/sensed AV delay 240/200ms, VV delay 0 ms, RV lead polarity true bipolar and LV lead Vector D1-M2 (distal bipole).
Comorbidities: poorly controlled hypertension, diabetes mellitus type 2 on oral anti-diabetics and chronic kidney disease KDIGO stage 3b.
Medication: Aspirin (100mg OD), Atorvastatin (40mg OD), Sacubitril/Valsartan (97/103mg BD), Aldactone (50mg OD), Carvedilol (25mg BD), Torasemide (10mg OD), Amlodipine (10mg OD) and Metformin (500mg BD).
Figure 1. Urgent 12 Lead ECG in A&E Department.
Figure 2. Side-by-side Comparison with previous ECGs