Abstract
Background
Structural cardiac adaptations due to hypertension (HTN) present a diagnostic challenge when differentiating from hypertrophic cardiomyopathy (HCM), using traditional imaging techniques such as echocardiography (echo). Cardiac magnetic resonance imaging (CMR) offers reproducible anatomical, functional quantification and myocardial tissue characterisation which discriminates between hypertension and HCM.
Purpose
To identify hypertensive individuals with undiagnosed HCM using CMR imaging.
Methods
100 consecutive hypertensive patients underwent CMR at a tertiary centre dedicated blood pressure clinic (55% male, mean age 51 years). In keeping with ESC guidelines, end diastolic wall thickness (EDWT) ≥15mm identified individuals within the “grey zone” between hypertension and with a potential HCM diagnosis. 19 individuals were referred on to the dedicated inherited cardiac conditions clinic for further evaluation. Four patients expressed a definitive LV phenotype and were diagnosed with HCM. CMR parameters were compared in three groups: Hypertensive (HTN), “grey zone” Hypertensive (GZH) and HCM.
Results
CMR demonstrated end diastolic wall thickness (EDWT) >11 mm in 50% of hypertensives. 73% of the referred patients were Afro-Caribbean (AC) and all 4 HCM patients were AC. All referrals demonstrated EDWTs ≥14mm, 9 (47%) demonstrated late gadolinium enhancement of which 3 (16%) had HCM. Three had asymmetrical septal hypertrophy – 2 were in the HCM cohort and one underwent endomyocardial biopsy confirming HTN. Left ventricular mass index (LVMI) was significantly higher in GZH compared to HTN (p<0.0001) and in HCM compared to HTN (p=0.0004). EDWT was significantly greater in GZH compared to HTN (p<0.0001) and in HCM compared to HTN (p=0.0002). There was no significant difference in these parameters between GZH and HCM.
Table 1. P-values for CMR data in hypertensive (HTN), gray zone hypertensive (GZH) and hypertrophic cardiomyopathy (HCM) cohorts CMR Parameter HCM vs. HTN GZH vs. HTN GZH vs. HCM EDVI NS p=0.025 NS EDWT p=0.0002 p<0.0001 NS LVMI p=0.0004 p<0.0001 NS
Conclusion
This study reports a 4% prevalence of HCM among hypertensive patients - 20 x greater than in the general population - which would be left undiagnosed using echo alone. Screening hypertensive individuals with CMR is not routine but we advocate its use in these individuals especially in Afro Caribbeans and in those in the “grey zone”, to identify undiagnosed HCM, which has significant implications for lifestyle modification and family screening.
Acknowledgement/Funding
Cardiac Risk in the Young
https://www.asianinstituteofresearch.org/JHMSarchives/To-Evaluate-Cerebral-Infarction-Among-Hypertensive-Patients-on-Magnetic-Resonance-Imaging-