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Canadian Journal of Cardiology

RELATIONSHIPS BETWEEN LEFT VENTRICULAR MASS AND QRS DURATION IN HYPERTROPHIC CARDIOMYOPATHY AND HYPERTENSIVE HEART DISEASE: A NEW DIAGNOSIS TOOL

      Background

      LVH in hypertensive heart disease (HHD) is known to increase QRS duration while Hypertrophic Cardiomyopathy (HCM) could be associated with narrower than normal QRS expected. Current diagnosis of HCM and HHD is based on imaging but suffers from considerable overlap and lack of specific feature. We aim to compare the relationship between left ventricular mass (LVM) and QRS duration in HCM and HHD to create a new diagnostic tool to identify HCM.

      Methods and Results

      We conducted a retrospective study in France (at the University Hospital of Toulouse and Bordeaux) and in Canada (at the University Cardiology and Pneumology Institute of Québec) comparing LV mass (LVM) and QRS duration according to different types of LV hypertrophy. Automatic measurement of LVM on MRI was correlated to automatic measurement of QRS duration on ECG. Uni- and multivariate analyses were performed comparing the relationship between QRS duration and LVM in HCM and HHD. A logistic regression formula was constructed with previously identified variables as associated with HCM diagnosis. The coefficient and Odds Ratio obtained from the final model were used to calculate the score. The score was then calculated for all patients, and the number of point threshold was chosen to obtain a highest sensibility and specificity. 686 patients were retrospectively included of whom 547 HCM (349 from France and 198 from Canada) and 139 HHD from France. Median QRS duration was 88±16 ms for HCM and 98±22 for HHD (p < 0,01). Median LVM was 91±30 and 82±31g/m2 respectively (p=0,03). QRS duration, LVM, hypertension, maximal wall thickness and LGE were significantly linked to HCM in multivariate analysis. An independent negative correlation was found between LVM and QRS duration in the HCM group, while the relationship was reverse in HHD. The HCM diagnostic score includes the following point assignments: High blood pressure +10 pts; MRI fibrosis +6 prs; QRS duration [>100]=0 pts [90-100]=+2 pts [ < 90]=+6 pts; LVM (g/m2) [ < 90]=0 pts, [90-110]=+1 pts, [110-130]=+2 pts, [>130]=+3 pts. A score higher than 7 is in favor of HCM with a sensitivity of 88% and a specificity of 70% (preliminary results).

      Conclusion

      QRS duration increases with LVM in HHD and decreases with LVM in HCM. These relationships were independent of other parameters. This HCM-specific relationship could be used as a diagnostic tool in clinical practice. These results need to be confirmed in larger studies.
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