[Antiarrhythmic drug effectiveness. Proposal for a new approach based on pharmacological hourly effects].
OBJECTIVE
To use a new approach in order to assess the antiarrhythmic drugs, based in the hourly autonomic effects and antiarrhythmic efficacy of sotalol.


METHODS
Sixteen patients were evaluated in a randomized double-blind placebo-controlled study. Patients were classified in group 1 (anti-arrhythmic efficacy) and group 2 (no antiarrhythmic efficacy). The following parameters were analyzed: 1) clinical variables as age, gender, cardiac disease and ventricular ectopies density; 2) drug effects on pNN50 in 24-hour and on mean hourly cardiac cycle length; 3) percentage of hourly ventricular ectopies distribution and its correlation with pNN50 and with mean hourly cardiac cycle length in all patients; 4) drug effects on mean hourly cardiac cycle length in groups 1 and 2; 5) correlation between hourly pNN50 and ventricular ectopies density after sotalol administration in groups 1 and 2; 6) hourly drug efficacy in groups 1 and 2 and correlation with pNN50.


RESULTS
Efficacy of the drug was present in 8 (50%) patients. Sotalol significantly increased 24-hour pNN50 (placebo 5.01 +/- 2.02%; after drug, 11.70 +/- 5.59%-p < 0.001), also increasing mean hourly cardiac cycle length during the day and night, in all patients (placebo 758.25 +/- 75.68 ms; after drug 967.71 +/- 80.17 ms-p < 0.000). It was noted that patients under placebo had different autonomic tonus; group 1 showed higher sympathetic activity as compared to group 2. Hourly drug efficacy was seen in 23 of 24-hour recordings in group 1 while it was not seen at any time in group 2.


CONCLUSIONS
Sotalol significantly increased parasympathetic cardiac activity. The anti-arrhythmic response was related to the autonomic tonus seen before and after drug administration.
Maia
I G
IG
Hospital Pró-Cardíaco/Pró-Ritmo, Rio de Janeiro.
Seixas
T N
TN
Costa
A M
AM
Perez
A K
AK
Alves
P A
PA
D000328:Adult; D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology / Q000627:therapeutic use*; D001145:Arrhythmias, Cardiac / Q000188:drug therapy*; D001341:Autonomic Nervous System / Q000502:physiology; D002940:Circadian Rhythm / Q000187:drug effects; D004311:Double-Blind Method; D015716:Electrocardiography, Ambulatory; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D013015:Sotalol / Q000494:pharmacology / Q000627:therapeutic use*
D000889:Anti-Arrhythmia Agents; D013015:Sotalol
Efficácia das drogas antiarrítmicas. Proposta para uma nova forma de avaliação baseada nos efeitos farmacológicos horários.