Discordance between effects of anti-ischemic therapy on ambulatory ischemia, exercise performance and anginal symptoms in patients with stable angina pectoris. The Angina and Silent Ischemia Study Group (ASIS).
OBJECTIVE
We sought to define the extent to which the therapeutic efficacy of three single-drug regimens on ambulatory ischemia paralleled efficacy on other clinical manifestations of ischemia, specifically exercise test performance and anginal symptoms.


BACKGROUND
Some studies have shown that the presence and severity of ambulatory ischemia are predictive of anginal symptoms and exercise test performance, whereas other studies have not. Less is known about effects of antianginal treatment and whether response to therapy for one clinical manifestation reflects therapeutic responses for other clinical manifestations.


METHODS
We studied 50 patients in the Angina and Silent Ischemia Study who had documented coronary disease, an exercise test positive for ischemia, the presence of ambulatory and asymptomatic ischemia on ambulatory electrocardiographic (ECG) Holter monitoring and stable anginal symptoms. Patients received maximally tolerated doses of sustained release propranolol (mean 293 mg/day), sustained release diltiazem (mean 350 mg/day), nifedipine (mean 79 mg/day) and placebo, each for 2-week periods in a double-blind, crossover fashion. Patients' responses to treatment were assessed by 48-h ambulatory ECG monitoring, exercise test (standard Bruce protocol) and diaries of angina. Levels of efficacy for each agent and for each clinical measure were compared using Spearman correlation analysis.


RESULTS
With placebo there was no correlation among the frequency of ischemic episodes by ambulatory ECG monitoring, exercise time to 1.0-mm ST segment depression or frequency of anginal episodes. Furthermore, for a given patient the efficacy of each active medication in reducing ambulatory ischemia was not correlated with response in anginal symptoms or exercise test performance (r = -0.21 to 0.24, p = NS). Within each of these clinical measures, efficacy of one drug was more strongly correlated with efficacy of another drug (r = 0.64 to 0.81 for ambulatory ischemia, 0.48 to 0.56 for exercise test performance and 0.16 to 0.54 for anginal symptoms).


CONCLUSIONS
Different measures of ischemia, specifically ambulatory ischemia assessed by ambulatory ECG monitoring, exercise performance on exercise test and anginal symptoms, are independent. Efficacy for each clinical end point must be assessed separately when considering response to drug treatment.
Borzak
S
S
Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115.
Fenton
T
T
Glasser
S P
SP
Shook
T L
TL
MacCallum
G
G
Young
P M
PM
Stone
P H
PH
D000368:Aged; D000787:Angina Pectoris / Q000188:drug therapy* / Q000503:physiopathology; D004110:Diltiazem / Q000494:pharmacology / Q000627:therapeutic use; D004311:Double-Blind Method; D015716:Electrocardiography, Ambulatory / Q000187:drug effects*; D005080:Exercise Test / Q000187:drug effects*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000188:drug therapy* / Q000503:physiopathology; D009543:Nifedipine / Q000494:pharmacology / Q000627:therapeutic use; D011237:Predictive Value of Tests; D011433:Propranolol / Q000494:pharmacology / Q000627:therapeutic use; D016896:Treatment Outcome; D014665:Vasodilator Agents / Q000494:pharmacology / Q000627:therapeutic use*
D014665:Vasodilator Agents; D011433:Propranolol; D004110:Diltiazem; D009543:Nifedipine