Impact of system delay on infarct size, myocardial salvage index, and left ventricular function in patients with ST-segment elevation myocardial infarction.
BACKGROUND
The association between reperfusion delay and myocardial damage has previously been assessed by evaluation of the duration from symptom onset to invasive treatment, but results have been conflicting. System delay defined as the duration from first medical contact to first balloon dilatation is less prone to bias and is also modifiable. The purpose was to evaluate the impact of system delay on myocardial salvage index (MSI) and infarct size in patients with ST-elevation myocardial infarction treated with primary percutaneous coronary intervention (PCI).


METHODS
In patients with ST-elevation myocardial infarction, MSI and final infarct size were assessed using cardiovascular magnetic resonance. Myocardial area at risk was measured within 1 to 7 days, and final infarct size was measured 90 ± 21 days after intervention. Patients were grouped according to system delay (0 to 120, 121 to 180, and >180 minutes).


RESULTS
In 219 patients, shorter system delay was associated with a smaller infarct size (8% [interquartile range 4-12%], 10% [6-16%], and 13% [8-17%]; P < .001) and larger MSI (0.77 [interquartile range 0.66-0.86], 0.72 [0.59-0.80], and 0.68 [0.64-0.72]; P = .005) for a system delay of up to 120, 121 to 180, and >180 minutes, respectively. A short system delay as a continuous variable independently predicted a smaller infarct size (r = 0.30, P < .001) and larger MSI (r = -0.25, P < .001) in multivariable linear regression analyses. Finally, shorter system delay (0-120 minutes) was associated with improved function (P = .019) and volumes of left ventricle (P = .022).


CONCLUSIONS
A shorter system delay resulted in smaller infarct size, larger MSI, and improved LV function in patients treated with primary PCI. Thus, this study confirms that minimizing system delay is crucial for primary PCI-related benefits.
Department of Cardiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark. jacoblonborg@gmail.com
Jacob
J
Lønborg
Mikkel Malby
MM
Schoos
Henning
H
Kelbæk
Lene
L
Holmvang
Jacob
J
Steinmetz
Niels
N
Vejlstrup
Erik
E
Jørgensen
Steffen
S
Helqvist
Kari
K
Saunamäki
Hans Erik
HE
Bøtker
Won Yong
WY
Kim
Christian Juhl
CJ
Terkelsen
Peter
P
Clemmensen
Thomas
T
Engstrøm
D002316:Cardiotonic Agents / Q000627:therapeutic use; D054059:Coronary Occlusion; D000077270:Exenatide; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000473:pathology* / Q000503:physiopathology / Q000628:therapy*; D015425:Myocardial Reperfusion; D009204:Myocardial Revascularization / Q000379:methods; D010455:Peptides / Q000627:therapeutic use; D012044:Regression Analysis; D013997:Time Factors; D014688:Venoms / Q000627:therapeutic use; D016277:Ventricular Function, Left / Q000502:physiology*
D002316:Cardiotonic Agents; D010455:Peptides; D014688:Venoms; D000077270:Exenatide