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JACC Vol. 51, No. 21, 2008 Epstein et al. e33 May 27, 2008:e1–62
enter
p. e33 or
3.2.4 in the PDF search box and press Enter 2 or 3 times. (The
Section reference listed in the Pocket Guidelines is incorrect.)
Risk factors for SCD in patients with hypertrophic cardiomyopathy
have been derived from multiple observational studies and registries.
A consensus document on HCM from the ACC and the European Society of
Cardiology categorized known risk factors for SCD as “major” and
“possible” in individual patients.
The major risk factors include:
-
Prior
cardiac arrest
-
Spontaneous
sustained VT
-
Spontaneous
nonsustained VT
-
Family
history of SCD
-
Syncope
-
LV thickness
greater than or equal to 30 mm
-
An abnormal
blood pressure response to exercise.
This consensus document also noted possible risk factors, which
include:
-
AF
-
Myocardial
ischemia
-
LV outflow
obstruction
-
High-risk
mutations
-
Intense
(competitive) physical exertion.
The severity of other symptoms, such as dyspnea, chest pain, and
effort intolerance, has not been correlated with increased risk of
SCD. A flat or hypotensive response to upright or supine exercise
testing in patients younger than 40 years old has been shown to be a
risk factor for SCD, although the positive predictive value of this
finding is low. A normal blood pressure response identifies a
low-risk group. The presence of nonsustained VT on Holter monitoring
has been associated with a higher risk of SCD, although the positive
predictive accuracy is relatively low. Recent analyses indicate that
in a high-risk HCM cohort, ICD interventions were frequent and were
highly effective in restoring normal sinus rhythm. However, an
important proportion of ICD discharges occur in primary prevention
patients who undergo implantation of the ICD for a single risk
factor. Therefore, a single risk marker of high risk for sudden
cardiac arrest may be sufficient to justify consideration for
prophylactic ICD implantation in selected patients. |