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Hypertrophic Cardiomyopathy in Black vs. White Patients
Study Questions:
What are the differences in clinical presentation, risk factor profile, and outcome of hypertrophic cardiomyopathy (HCM) between African/Afro-Caribbean (black) and white patients?
Methods:
A total of 425 consecutive patients from three cardiomyopathy clinics in London, UK, were evaluated for presenting symptoms, electrocardiogram (ECG) changes, phenotypic characteristics, and outcome. Separate criteria were used for the definition of HCM in hypertensive and nonhypertensive patients. The primary outcome was a composite of cardiovascular death, cardiac arrest, or appropriate implantable cardioverter-defibrillator (ICD) therapy.
Results:
Of the 425 consecutive patients with HCM, 163 were black and 262 were Caucasian with a mean age of 52.5 ± 16.6 years. The proportion of patients presenting with symptoms at the time of initial evaluation was similar between black and white patients (82.2% vs. 77.1%, p = 0.208). A fortuitous diagnosis of HCM was noted in 31.3% of black patients compared to 19.1% of white patients (p = 0.004). A history of hypertension was more common in black versus white patients (58.3% vs. 31.7%, p < 0.001), while a family history of HCM was more common in white than in black patients (29.0% vs. 19.0%, p = 0.021). An abnormal ECG was more common in black than in white patients (98.2% vs. 90.5%, p = 0.002) and ECG evidence for left ventricular hypertrophy was more common in black than in white patients (54.9% vs. 36.3%, p < 0.001). Similarly, T-wave inversion was more common in black than in white patients (91.4% vs. 73.0%, p < 0.001). A resting left ventricular outflow tract ≥30 mm Hg was seen in 21.4% of white patients and 7.5% of black patients (p < 0.001). Both apical hypertrophy (22.2%) and concentric hypertrophy (9.2%) patterns were more prevalent in black than in white patients (10.7% and 1.5%, respectively). The prevalence of risk factors for adverse outcomes in HCM was similar in black and white patients. Among the 409 patients for whom survival analysis was available, 5.9% died from cardiovascular causes, 1.7% survived a cardiac arrest, and 2.7% received appropriate ICD therapy. Survival curves demonstrated no differences between black and white patients in freedom from the primary outcome. Both hypertension and nonsustained ventricular tachycardia on monitoring were independent predictors of the primary outcome.
Conclusions:
In comparing black and white patients with HCM, there are differences in presenting features including prevalence of hypertension and an abnormal ECG. Apical and concentric hypertrophy are more common in black patients and may have implications for appropriate diagnosis, especially in those with concurrent hypertension. Overall freedom from adverse events is similar.
Perspective:
This study from dedicated HCM clinics in London demonstrates important racial differences in the presentation of HCM. Notably, ECG abnormalities are noted in virtually all (98.2%) black patients, with hypertrophic myopathy and T-wave inversion noted in 91.4%. Apical and concentric variants of hypertrophic myopathy were noted in almost one third of the black patients. This study also nicely addresses the complexities of establishing a diagnosis of HCM in a patient population with a higher prevalence of hypertension, which may make establishing a conclusive diagnosis problematic. Of note, a combination of hypertension at the time of initial evaluation and a history of nonsustained ventricular tachycardia conferred a substantially worse prognosis than the absence of these features. While there were distinct differences between the black and white HCM patients with respect to family history, presence of hypertension, and resting ECG abnormalities, there were no differences in the prevalence of established risk factors for adverse outcome, and no difference in the overall outcome.
Keywords: Arrhythmias, Cardiac, Cardiomyopathy, Hypertrophic, Defibrillators, Implantable, Electrocardiography, Heart Arrest, Heart Failure, Hypertension, Hypertrophy, Left Ventricular, Outcome Assessment, Health Care, Risk Factors, Tachycardia, Ventricular
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