Drop-out from cardiovascular magnetic resonance in a randomized controlled trial of ST-elevation myocardial infarction does not cause selection bias on endpoints.
BACKGROUND
The extent of selection bias due to drop-out in clinical trials of ST-elevation myocardial infarction (STEMI) using cardiovascular magnetic resonance (CMR) as surrogate endpoints is unknown. We sought to interrogate the characteristics and prognosis of patients who dropped out before acute CMR assessment compared to CMR-participants in a previously published double-blinded, placebo-controlled all-comer trial with CMR outcome as the primary endpoint.


METHODS
Baseline characteristics and composite endpoint of all-cause mortality, heart failure and re-infarction after 30 days and 5 years of follow-up were assessed and compared between CMR-drop-outs and CMR-participants using the trial screening log and the Eastern Danish Heart Registry.


RESULTS
The drop-out rate from acute CMR was 28% (n = 92). These patients had a significantly worse clinical risk profile upon admission as evaluated by the TIMI-risk score (3.7 (± 2.1) vs 4.0 (± 2.6), p = 0.043) and by left ventricular ejection fraction (43 (± 9) vs. 47 (± 10), p = 0.029). CMR drop-outs had a higher incidence of known hypertension (39% vs. 35%, p = 0.043), known diabetes (14% vs. 7%, p = 0.025), known cardiac disease (11% vs. 3%, p = 0.013) and known renal function disease (5% vs. 0%, p = 0.007). However, the 30-day and 5-years composite endpoint rate was not significantly higher among the CMR drop-out ((HR 1.43 (95%-CI 0.5; 3.97) (p = 0.5)) and (HR 1.31 (95%-CI 0.84; 2.05) (p = 0.24)).


CONCLUSIONS
CMR-drop-outs had a higher incidence of cardiovascular risk factors at baseline, a worse clinical risk profile upon admission. However, no significant difference was observed in the clinical endpoints between the groups.
Department of Cardiology, The Heart Centre, Rigshospitalet, Copenhagen University Hospital, Blegdamsvej 9, 2100, Copenhagen, Denmark. peter.noerkjaer.laursen@regionh.dk.
Peter Nørkjær
PN
Laursen
Department of Cardiology, The Heart Centre, Rigshospitalet, Copenhagen University Hospital, Blegdamsvej 9, 2100, Copenhagen, Denmark.
L
L
Holmvang
Department of Cardiology, Roskilde Hospital, Roskilde, Denmark.
H
H
Kelbæk
Department of Cardiology, The Heart Centre, Rigshospitalet, Copenhagen University Hospital, Blegdamsvej 9, 2100, Copenhagen, Denmark.
N
N
Vejlstrup
Department of Cardiology, The Heart Centre, Rigshospitalet, Copenhagen University Hospital, Blegdamsvej 9, 2100, Copenhagen, Denmark.
T
T
Engstrøm
Department of Cardiology, The Heart Centre, Rigshospitalet, Copenhagen University Hospital, Blegdamsvej 9, 2100, Copenhagen, Denmark.
J
J
Lønborg
D002423:Cause of Death / Q000639:trends; D001026:Coronary Artery Bypass / Q000379:methods*; D003718:Denmark / Q000453:epidemiology; D004311:Double-Blind Method; D023381:Endpoint Determination / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D000072657:ST Elevation Myocardial Infarction / Q000175:diagnosis* / Q000401:mortality / Q000628:therapy; D015983:Selection Bias; D015996:Survival Rate / Q000639:trends; D015912:Thrombolytic Therapy / Q000379:methods*; D013997:Time Factors; D016277:Ventricular Function, Left / Q000502:physiology