Cardiac resynchronisation therapy in optima forma

The electrocardiogram in Fig. 2 shows atrioventricular (AV) sequential pacing at a rate of 60 bpm with QRS duration ~90 ms. The QRS morphology is consistent with conduction system pacing, in particular selective His bundle pacing (HBP) with correction of LBBB.

HBP is a cardiac pacing technique with the potential of preserving or restoring normal His-Purkinje activation in the presence of AV conduction block or BBB. A prerequisite for successful HBP in the setting of LBBB is the presence of a proximal or intra-His conduction block, which can be circumvented by pacing the distal His bundle and thereby recruiting the otherwise ‘healthy’ left-sided conduction system. LBBB can be corrected with HBP in up to 80% of patients depending on the site of the block [1], and the conduction block site correlates reasonably well with surface ECG. The Strauss criteria have a positive predictive value of 71% for identifying patients eligible for corrective HBP [2]. Although, as of yet, there is no clear benefit of HBP over traditional biventricular pacing because this has not been investigated properly, HBP is potentially the ultimate form of cardiac resynchronisation therapy [3].

In our patient, pathological Q waves in the inferior and lateral leads, which were previously not visible (see Fig. 1), were revealed postoperatively in conjunction with a dominant R wave in the right precordial leads (Fig. 2), as a result of normalisation of ventricular electrical activation. These ECG findings could be related to the findings of cardiac magnetic resonance imaging (MRI), which revealed transmural inferolateral myocardial infarction (Fig. 3).