Anatomical Connections Between the Papillary Muscles and the Ventricular Myocardium: Correlation With QRS Variability of Ventricular Arrhythmias.

BACKGROUND: Papillary muscles (PM) ventricular arrhythmias (VAs) exhibit QRS variability, attributed to anisotropy. ECG inconsistencies such as late precordial transition (TZ) and discordant QRS axis may not be solely explained by anisotropic conduction. We sought to determine the presence of anatomic connections of the PM and correlate them with ECG inconsistencies and ablation results.

METHODS: Patients with prior PM VAs catheter ablation (N=33/66 PMs) were prospectively evaluated with cardiac resonance for the presence of muscular connection (PMCs) away from the PM base. Specific ECG characteristics including early (consistent TZ) and late (inconsistent-ITZ) TZ or inconsistent (IQA) or consistent QA QRS axis were correlated with PMCs.

RESULTS: Thirty-five PMs exhibited clinical VAs (N=29 posteromedial PM and N=6 anterolateral PM). PM VAs with ITZ and IQA were observed in 11 and 9 PMs, respectively. In total, 41 PMs (62%) exhibited 90 PMCs. Arrhythmogenic PMs (N=35) exhibited higher number of PMCs (72 versus 18; P=0.01). Patients with ITZ and IQA exhibited 100% prevalence of PMCs. Those with consistent TZ and consistent QA showed 40% and 26% prevalence of PMCs, respectively. ITZ and IQA predicted the presence of PMCs with 59% of 28% sensitivity; and 100% of 100% specificity, respectively. Type-specific PMCs were more prevalent in patients with ECG inconsistencies. Those PMs are exhibiting clinical recurrence after ablation presented higher prevalence of PMCs (91% versus 60%; P=0.04).

CONCLUSIONS: PMCs are highly prevalent in patients with PM VAs. A direct correlation exists between PM VAs ECG inconsistencies and type-specific PMCs. Patients with ITZ or IQA exhibited PMC 100% prevalence. Recurrence was higher among patients with PMCs.