A patient with myotonic dystrophy Type 1 may be at risk for sudden death. Groh et al identified risk factors associated with sudden death in these patients. The authors are from Indiana University, Pennsylvania State University, University of Rochester, and SUNY Stonybrook.


Risk factors for sudden death:

(1) atrial tachyarrhythmia

(2) severe ECG abnormality


Severe ECG abnormalities included:

(1) rhythm other than sinus

(2) PR interval >= 240 msec

(3) QRS duration >= 120 msec

(4) second or third degree atrioventricular (AV) block



• minimum number of risk factors present: 0

• maximum number of risk factors present: 2

• The risk for sudden death increases with the number of risk factors.

Number of Risk Factors

Risk of Sudden Death


very low


low to moderate


moderate to high


To read more or access our algorithms and calculators, please log in or register.