Misclassification of hypertrophic cardiomyopathy: validation of diagnostic codes

Figures & data

Table 1 Characteristics of 88 patients with validated HCM diagnosis

Variable	HCM patients
Age, mean (SD)a	65.8 (15.7)
Male sex, n (%)	46 (52.2)
Diabetes mellitus, n (%)	11 (12.5)
Hypertension, n (%)	30 (34.1)
Atrial fibrillation, n (%)	24 (27.3)
Stroke, n (%)	8 (9.1)
COPD, n (%)	6 (6.8)
LVEF <50%a, n (%)	5 (5.7)
Myectomy, n (%)	15 (17.0)
Alcohol septal ablation, n (%)	1 (1.1)
Ischemic heart diseaseb, n (%)	8 (35.8)
Renal failure, creatinine >120 μmol/L, n (%)	4 (4.5)
Maximal wall thicknessc (mm), mean (SD)	19.2 (2.9)
Genopositive, n (%)	22 (25)
Heart transplant, n (%)	1 (1.1)
ICD, n (%)	12 (13.6)
Pacemaker, n (%)	10 (11.4)

Notes:

a Among living patients.

b Ischemic heart disease requiring intervention.

c Among patients without previous myectomy/alcohol septal ablation.

Abbreviations: COPD, chronic obstructive pulmonary disease; HCM, hypertrophic cardiomyopathy; ICD, implantable cardioverter defibrillator; LVEF, left ventricular ejection fraction; SD, standard deviation.

Table 2 Patients with HCM-related diagnostic codes who were misclassified

Misclassified as HCM	Misclassified (n=41), n (%)	Cohort (n=129), n (%)
Hypertension	13 (31.7)	10.1
Aortic stenosis	9 (22.0)	7.0
Amyloidosis	4 (9.8)	3.1
Dilated CM, nonischemic	4 (9.8)	3.1
Dilated CM, ischemic	2 (4.9)	1.6
Left ventricular noncompaction CM	1 (2.4)	0.8
Takotsubo CM	1 (2.4)	0.8
Aortic insufficiency	2 (4.9)	1.6
Myocardial infarction	2 (4.9)	1.6
Pulmonary stenosis, VSD	1 (2.4)	0.8
Atrioventricular block, third degree	1 (2.4)	0.8
Athlete’s heart	1 (2.4)	0.8

Abbreviations: CM, cardiomyopathy; HCM, hypertrophic cardiomyopathy; VSD, ventricular septal defect.

Table S1 Patients with HCM and concomitant hypertension

Correct HCM with hypertension (n=30)	Description
Female, born 1922, died 2015	Septal and midseptal hypertrophy 17 mm, ECG repolarization abnormalities, maximal LVOT gradient 68 mmHg, mild controlled hypertension
Female, born 1924, died 2013	Septal hypertrophy 18 mm, mean gradient 58 mmHg, pacemaker due to reduced obstruction, ECG repolarization abnormalities, mild controlled hypertension
Female, born 1926, died 2015	Septal hypertrophy 17 mm, Vmax 2.8 m/s, ECG repolarization abnormalities, mild controlled hypertension with a short history
Female, born 1928, died 2016	Septal and midseptal hypertrophy 20 mm, Vmax 3.8 m/s, mild controlled hypertension
Male, born 1931, died 2013	Septal hypertrophy 17 mm, MYBPC positive, mild hypertension
Female, born 1931, died 2016	Septal hypertrophy 20 mm, Vmax 4.2 m/s, mild controlled hypertension, heredity for sudden death
Female, born 1933, died 2013	Septal hypertrophy 17 mm, Vmax 2.6 m/s, unexplained syncope, ECG repolarization abnormalities, mild controlled hypertension
Female, born 1937, died 2012	Septal, midseptal hypertrophy 21 mm, ECG repolarization abnormalities, mild controlled hypertension
Female, 95 years	Septal hypertrophy 22 mm, ECG repolarization abnormalities, mild controlled hypertension
Male, 89 years	Apical hypertrophy, not reported maximal thickness, ECG repolarization abnormalities, mild controlled hypertension
Female, 85 years	Septal-apical hypertrophy 17 mm, grandmother sudden death at 56 years, MYBPC, mild controlled hypertension
Female, 83 years	Inferolateral hypertrophy 19 mm, ECG repolarization abnormalities, mild controlled hypertension
Female, 81 years	Septal hypertrophy 20 mm, 2.3 m/s, ECG repolarization abnormalities, mild controlled hypertension
Female, 78 years	Septal hypertrophy 26 mm, 4.1 m/s, myectomy, ECG repolarization abnormalities, mild controlled hypertension
Female, 76 years	Septal hypertrophy 19 mm, 3.7 m/s, ECG repolarization abnormalities, mild controlled hypertension
Male, 74 years	Septal-midseptal hypertrophy 24 mm, 2.4 m/s, ECG repolarization abnormalities, mild controlled hypertension
Male, 74 years	Septal hypertrophy 26 mm, myectomy, genopositive, ECG repolarization abnormalities, mild controlled hypertension
Female, 74 years	Septal hypertrophy 18 mm, 3.1 m/s, ECG repolarization abnormalities, mild controlled hypertension
Female, 74 years	Septal hypertrophy 21 mm, 2.2 m/s, ECG repolarization abnormalities, mild controlled hypertension
Female, 73 years	Septal hypertrophy 19 mm, 4.4 m/s, ECG repolarization abnormalities, mild controlled hypertension
Female, 73 years	Septal hypertrophy 22 mm, 4.8 m/s, ECG repolarization abnormalities, mild controlled hypertension
Male, 71 years	Septal hypertrophy 21 mm, 2.9 m/s, ECG repolarization abnormalities, mild controlled hypertension
Male, 71 years	Septal hypertrophy 23 mm, myectomy, 5.6 m/s, ECG repolarization abnormalities, mild controlled hypertension
Female, 71 years	Septal hypertrophy 24 mm, myectomy, sudden death of two cousins, ECG repolarization abnormalities, mild controlled hypertension
Female, 70 years	Posterior hypertrophy 19 mm, ECG repolarization abnormalities, mild controlled hypertension
Female, 66 years	Septal hypertrophy, myectomy, MYH7 positive, ECG repolarization abnormalities, mild controlled hypertension
Male, 60 years	Septal hypertrophy 23 mm, ECG repolarization abnormalities, mild controlled hypertension
Male, 57 years	Septal hypertrophy 22 mm, ECG repolarization abnormalities, mild controlled hypertension
Male, 57 years	Septal hypertrophy 20 mm, mean gradient 80 mmHg, ECG repolarization abnormalities, mild controlled hypertension
Male, 54 years	Septal hypertrophy 19 mm, maximum gradient 39 mmHg, unexplained syncope ECG repolarization abnormalities, mild controlled hypertension

Abbreviations: ECG, electrocardiogram; HCM, hypertrophic cardiomyopathy; LVOT, left ventricular outflow tract; MYBPC, myosin binding protein C; V_max, velocity maximal.

Table S2 Patient with hypertension misclassified as HCM

Misclassified as HCM	Reclassified (n=13) as hypertension
Female, 88 years	Septum 14 mm, hypertension for several years
Female, born 1932, died 2016	Severe hypertension for several years but no cardiac imaging ever done
Male, 78 years	Concentric hypertrophy 16 mm, uncontrolled hypertension for several years
Female, 77 years	“Minimal hypertrophy” at echocardiography report without specific measurements. Malignant hypertension with systolic blood pressure >220 mmHg at repeated measurements. Never reached controlled hypertension
Female, 77 years	Septal bullae 14.5 mm, hypertension for at least 16 years
Female, 76 years	Minimal hypertrophy and 16 mm localized basal septal hypertrophy. Hypertension for several years and regression of hypertrophy
Male, 76 years	Severe hypertension for several years, partly uncontrolled. No cardiac imaging
Female, born 1941, died 2016	Septum 15–18 mm at different echocardiography examinations and mild aortic stenosis. Overestimation of hypertrophy (18 mm) attributed to inexperienced examiner. Later estimated at 15 mm. History of hypertension for at least 12 years
Female, 72 years	Septum 15–17 mm and concentric hypertrophy. Severe hypertension and repeatedly systolic blood pressure >170 mmHg despite medication (probably not fully compliant)
Male, 72 years	Hypertension. Echocardiography did not show hypertrophy (10 mm)
Female, 64 years	Slight proximal septal hypertrophy, maximum 15–16 mm, on echocardiogram. Uncontrolled hypertension for several years
Female, 48 years	Repeated echocardiograms but septum never >13 mm, no obstruction, no systolic anterior motion. Controlled hypertension of unknown duration
Male, 46 years	Septum 14–15 mm, no obstruction, no systolic anterior motion. Malignant hypertension 240 mmHg, uncontrolled hypertension for several years

Abbreviation: HCM, hypertrophic cardiomyopathy.