DISCUSSION
Because all six hospitals included in the study were closely located
geographically and were managed within the same healthcare system, it
was surprising to find significant differences among them in the
frequency of variables that could increase D2B time. Identified in the
study were differences in age, ambulance versus walk-in, scenario of
admission, and patient-related variables (cardiac arrest, need for
intubation, need for radiologic evaluation, and inconclusive ECGs).
However, none of these variables were consistently different between the
higher and lower performing hospitals. It is possible that differing
socioeconomic variables (such as poverty and level of education)
affected outcomes among the six hospitals.
The American Heart Association has recommended that at least 75% of
STEMI patients receive the first ECG < 10 minutes of
admission.3 Collectively, the percent of adherence to
this recommendation among the six hospitals was 83.1% (median 4
minutes, IQR 1-8). The six hospitals included in this study collectively
performed above the minimal adherence score for a D2B time ≤90 minutes
(87.8% adherence as opposed to 75%, respectively).3Nonetheless, there was considerable variation among the six hospitals;
the two highest performing hospital complied in 94.9% and 97.1% of the
cases, while the lowest performing hospital complied in 79.1% of the
cases. It is difficult to explain why this wide range of compliance
occurred; as there was no consistent pattern in the distribution of
suspect variables among the six sites.
An expected finding was that patients with D2B times >90
minutes had a significantly higher mortality than those with D2B times< 90 minutes. However, the data on mortality is not
conclusive because the study lacked information describing whether the
mortality was cardiac or non-cardiac related as well as there was no
documentation on comorbidity or underlying cardiac disease such as
left-ventricular function, valvular heart disease, prior congestive
heart failure, prior stent or coronary artery bypass graft.
Perhaps the most important finding of our study was the effect of the
scenario of admission to the CCL. Scenarios B and C were associated with
significantly better D2B times than was Scenario A. This is reasonable,
given that these scenarios involve EMS admission with ECGs performed in
the field. Scenario B is best in that it bypassed an ED admission and
patients are transported directly to the CCL. An expected finding was
that the presence of confounders significantly affected D2B time. While
there were insufficient data to assess the significance of non-patient
related confounders on D2B time, the presence of at least one
patient-related confounder greatly increased D2B time.