Patients with hypertrophic cardiomyopathy may suffer sudden death. Elliott et al identified risk factors for sudden death and correlated these with survival. The authors are from St. George's Hospital Medical School in London.
There was a higher probability of sudden death or placement of cardioverter-defibrillator with increasing wall thickness.
(1) The relative risk for each 5 mm increment in wall thickness was 1.31.
(2) Patients with a wall thickness >= 30 mm had a relative risk of 2.07 when compared to those with a wall thickness < 30 mm.
Additional risk factors:
(1) nonsustained ventricular tachycardia: >= 1 run of >= 3 consecutive ventricular extrasystoles at a rate of > 120 beats per minute and lasting > 30 seconds
(2) abnormal blood pressure response to upright exercise: either (a) a failure of systolic blood pressure to rise > 25 mm Hg from baseline, or (b) fall > 10 mm Hg from maximum systolic blood pressure. This is recorded as a risk factor of the patient's age is <= 40.
(3) family history of sudden death, with >= 2 relatives with sudden cardiac death before age 40
(4) recurrent unexplained syncope, with >= 2 episodes within a year of the index echocardiogram
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|
5 Year Survival and Number of Additional Risk Factors
|
|
LV wall thickness
|
0
|
1
|
2
|
3
|
|
< 15 mm
|
0.98
|
0.96
|
0.92
|
0.85
|
|
15 – 19 mm
|
0.97
|
0.95
|
0.90
|
0.81
|
|
20 – 24 mm
|
0.97
|
0.94
|
0.88
|
0.77
|
|
25 – 29 mm
|
0.96
|
0.92
|
0.85
|
0.72
|
|
>= 30 mm
|
0.95
|
0.90
|
0.81
|
0.66
|
where:
• No data is given for survival in patients with 4 risk factors.
• For the abnormal blood pressure response to exercise: It is unclear to me whether to apply this only if the patient's current age is <= 40, or to use it as a risk factor that can be applied at an older age once identified.
Conclusions:
(1) A patient with a left ventricular wall thickness >= 30 mm and no risk factors does not need aggressive prophylactic therapy.
(2) A patient with a thinner wall thickness but multiple risk factors cannot be reassured that they are at low risk.
