Nonsystem Delays in STEMI Patients Predict In-Hospital Mortality

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In patients with ST-segment elevation myocardial infarction presenting for primary percutaneous coronary intervention (PCI), nonsystem reasons for delay are common and linked with high in-hospital mortality, according to results published in the April 23, 2013, issue of the Journal of the American College of Cardiology. However, the association with mortality may simply be a marker of higher risk patients, an editorial suggests.

For the retrospective analysis, Rajesh V. Swaminathan, MD, of Weill Cornell Medical College (New York, NY), and colleagues looked at 82,678 STEMI patients enrolled in the National Cardiovascular Data Registry CathPCI Registry at 1,172 centers who underwent primary PCI within 24 hours of symptom onset from January 2009 to June 2011.

Delays Not Unusual

Median D2B time was 65 minutes, with 18.9% of patients reporting times longer than the guideline-recommended 90 minutes. Nonsystem delays occurred in 12,146 patients (14.7%) and included:

• Cardiac arrest/need for intubation: 37.4%
• Difficulty in crossing lesion: 18.8%
• Challenging vascular access: 8.4%
• Delay in providing procedure consent: 4.4%
• Other: 31.0%

Presence of a nonsystem delay did not necessarily equate to a D2B time of greater than 90 minutes. Overall, 47% of patients with nonsystem delays still underwent device deployment before the 90 minute mark. Delays due to providing consent were the longest, but 67% of affected patients missed the 90 minute cutoff. Moreover, patients with delays due to cardiac arrest/intubation had the shortest lags in treatment (table 1).

Table 1. Door-to-Balloon Times

 
In-hospital mortality for patients with nonsystem delays was higher than for those without them (15.1% vs. 2.5%; P < 0.0001). Death rates were highest for those with cardiac arrest/intubation (29%) and lowest for patients in whom there was difficulty crossing lesion (5.6%). Each of these rates was higher compared with nondelayed patients (P > 0.0001).

Multivariable analysis found mortality risk to be elevated by delays due to cardiac arrest/intubation (OR 3.4; 95% CI 3.1-3.8; P < 0.001) and nonsystem delays as a whole (OR 1.7; 95% CI 1.5-1.9; P < 0.001). Also, adjusted in-hospital mortality was similar for both cardiac arrest-related and all other combined nonsystem delays regardless of door-to-balloon time (P < 0.001 for each comparison).

Post-procedure adverse events were also more common in patients delayed for nonsystem reasons compared with those who lacked nonsystem delays (P < 0.0001 for each comparison).

System Solutions Will Help

“The frequency of nonsystem reasons for delay may account for disparities seen between guidelines and clinical practice,” Dr. Swaminathan and colleagues write. For example, they suggest that a “cultural bias or language barrier” could have contributed to the delays in obtaining informed consent.

“Some nonsystem reasons for delay may have system solutions to improve quality of care,” they continue, suggesting that making available resources such as interpreters may help increase efficiency. “These system solutions to nonsystem reasons for delay should be scrutinized to discern any potential improvements in the quality of care delivered to this high-risk group of patients.”

In addition, the authors question whether or not further improvements in D2B time will actually improve mortality, writing that “differences in clinical risk presentation and symptom onset-to-door time may explain why mortality does not always correlate with [D2B time].”

Delays Inevitable in High-Risk Patients

In an accompanying editorial, Cindy L. Grines, MD, and Theodore Schreiber, MD, both of Detroit Medical Center Cardiovascular Institute (Detroit, MI), write that the study importantly “demonstrates that delay, in and of itself, is probably not responsible for huge differences in mortality.” Rather, it serves as a marker for higher risk patients. “However, the frail nature of patients with nonsystem delay was further demonstrated by the marked increase in noncardiac events such as stroke, bleeding, vascular complications, and renal failure; events that are not related to delay in reperfusion,” they write.

Perhaps the focus should be turned away from D2B time, Drs. Grines and Schreiber suggest. Continuing to home in on the issue “may encourage some physicians to ‘game the system’ by withholding primary PCI in patients who are sick or who are anticipated to have long [D2B times].”

Further improvements will come from an emphasis on providing primary PCI to more patients, as well as “more widespread use of prehospital electrocardiograms, bypassing a non-PCI center in preference for a tertiary care center, better public education about recognizing symptoms, and calling 911,” they conclude.

Study Details

Overall, patients with nonsystem delays were more likely to be older, female, or African-American, and have a history of hypertension, diabetes, previous MI, previous congestive heart failure, previous CABG, dialysis, cerebrovascular disease, peripheral vascular disease, or chronic lung disease compared with patients who lacked nonsystem delays.

 

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Sources:
1. Swaminathan RV, Wang TY, Kaltenbach LA, et al. Nonsystem reasons for delay in door-to-balloon time and associated in-hospital mortality: A report from the National Cardiovascular Data Registry. J Am Coll Cardiol. 2013;61:1688-1695.

2. Grines CL, Schreiber T. Primary percutaneous intervention: The deception of delay. J Am Coll Cardiol. 2013;61:1686-1697.

 

 

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