Lown and his colleagues proposed a classification of premature ventricular beats based on risk of death after myocardial infarction.
no ventricular premature beats
less than 30 ventricular premature beats per hour
30 or more ventricular premature beats per hour
multiform/polymorphic ventricular premature beats
repetitive ventricular premature beats
• couplets (2 consecutive ventricular extrasystoles)
• monomorphic ventricular tachycardia runs (salvos, 3 or more consecutive ventricular extrasystoles)
R on T phenomenon (ventricular premature beat on preceding T wave)
• In general, the prognosis worsens as the grade increases.
• Bigger and Weld (1981) found that grade 4 arrhythmias had greater risk than grade 5 arrhythmias:
0% (only 2 patients)
(Table 2, page 719, Bigger and Weld, 1981)
• The R on T phenomenon is now considered especially dangerous only in the presence of acute ischemia.
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