Association between Left Ventricular Wall Thickness and Heart Rate Variability with Complex Ventricular Arrhythmia in Hypertrophic Cardiomyopathy

Abstract

Objective: To demonstrate the association between the maximal left ventricular (LV) wall thickness and the late gadolinium enhancement (LGE) by cardiac magnetic resonance (CMR) and heart rate variability (HRV) with complex ventricular arrhythmia (VA) in patients with hypertrophic cardiomyopathy (HCM). Materials and Methods: The present study was a retrospective study. Fifty-seven HCM patients who underwent CMR and Holter monitoring at Siriraj Hospital, Bangkok, Thailand, were identified and included. Complex VA was defined as Lown grading system type 4a or 4b as couplet or non-sustained ventricular tachycardia. Standard deviation of normal RR-interval (SDNN) was used to assess HRV. Results: The authors studied 57 patients, 40 (70.2%) patients had LGE, and 13 (22.8%) patients had complex VA. Complex VA was demonstrated in 11 (27.5%) patients in the LGE group compared with two (11.8%) in those without (p=0.304), and four (57.1%), and nine (18.0%) in patients had a maximal LV wall thickness of 25 mm or more and less than 25 mm, respectively (p=0.041). SDNN was 100.98±29.82 ms versus 123.85±35.12 ms (p=0.015) in the LGE group compared with the no-LGE group, and 89.08±25.39 ms versus 113.34±33.06 ms (p=0.018) in patients with and without complex VA. Multivariate analysis showed significant associations of maximal LV wall thickness of 25 mm or more and SDNN of less than 105 ms with complex VA with odds ratios of 6.71 (95% confidence interval [CI] 1.09 to 41.14; p=0.040) and 5.15 (95% CI 1.14 to 23.30; p=0.033), respectively. Conclusion: In HCM patients, increased LV wall thickness and a reduction in SDNN are associated with complex VA. The present study supports the utility of CMR and HRV for risk stratification of patients with HCM. Keywords: Heart rate variability; Maximal left ventricular wall thickness; Complex ventricular arrhythmia; Hypertrophic cardiomyopathy