Noninvasive risk assessment early after a myocardial infarction the REFINE study.
OBJECTIVE
This study sought to determine whether combined assessment of autonomic tone plus cardiac electrical substrate identifies most patients at risk of serious events after myocardial infarction (MI) and to compare assessment at 2 to 4 weeks versus 10 to 14 weeks after MI.


BACKGROUND
Methods to identify most patients at risk of serious events after MI are required.


METHODS
Patients (n = 322) with an ejection fraction (EF) <0.50 in the initial week after MI were followed up for a median of 47 months. Serial assessment of autonomic tone, including heart rate turbulence (HRT), electrical substrate, including T-wave alternans (TWA), and EF was performed, interpreted blinded, and categorized using pre-specified cut-points where available. The primary outcome was cardiac death or resuscitated cardiac arrest. All-cause mortality and fatal or nonfatal cardiac arrest were secondary outcomes.


RESULTS
Mean EF significantly increased over the initial 8 weeks after MI. Testing 2 to 4 weeks after MI did not reliably identify patients at risk, whereas testing at 10 to 14 weeks did. The 20% of patients with impaired HRT, abnormal exercise TWA, and an EF <0.50 beyond 8 weeks post-MI had a 5.2 (95% confidence interval [CI] 2.4 to 11.3, p < 0.001) higher adjusted risk of the primary outcome. This combination identified 52% of those at risk, with good positive (23%; 95% CI 17% to 26%) and negative (95%; 95% CI 93% to 97%) accuracy. Similar results were observed for the secondary outcomes.


CONCLUSIONS
Impaired HRT, abnormal TWA, and an EF <0.50 beyond 8 weeks after MI reliably identify patients at risk of serious events. (Assessment of Noninvasive Methods to Identify Patients at Risk of Serious Arrhythmias After a Heart Attack; http://www.clinicaltrials.gov/ct/show/NCT00399503?order=1; NCT00399503).
Exner
Derek V
DV
Libin Cardiovascular Institute of Alberta, Calgary, Canada; Department of Community Health Sciences, University of Calgary, Calgary, Canada.
Kavanagh
Katherine M
KM
Slawnych
Michael P
MP
Mitchell
L Brent
LB
Ramadan
Darlene
D
Aggarwal
Sandeep G
SG
Noullett
Catherine
C
Van Schaik
Allie
A
Mitchell
Ryan T
RT
Shibata
Mariko A
MA
Gulamhussein
Sajad
S
McMeekin
James
J
Tymchak
Wayne
W
Schnell
Gregory
G
Gillis
Anne M
AM
Sheldon
Robert S
RS
Fick
Gordon H
GH
Duff
Henry J
HJ
D000368:Aged; D017704:Baroreflex / Q000502:physiology; D004562:Electrocardiography / Q000379:methods*; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D006323:Heart Arrest / Q000209:etiology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications* / Q000401:mortality / Q000503:physiopathology*; D011237:Predictive Value of Tests; D018570:Risk Assessment / Q000379:methods; D013318:Stroke Volume / Q000502:physiology; D013997:Time Factors