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Delays in symptom onset-to-balloon time associated with poor outcomes in patients with STEMI
Despite gains made in door-to-balloon time, delays in symptom onset-to-balloon time are contributing to poor outcomes for patients with STEMI, according to new data from the HORIZONS-AMI study.
“The decrease in median door-to-balloon time (DBT) in recent years has not resulted in a reduction in mortality in STEMI patients,” Roxana Mehran, MD, director of interventional cardiovascular research and clinical trials, Zena and Michael A. Weiner Cardiovascular Institute, Icahn School of Medicine at Mount Sinai, said in a press release. “This study highlights the need to reconsider the role of [DBT] as a performance metric and examine the utility of a broader metric of systems delay such as first medical contact-to-balloon time as well as total ischemic time.”
Mehran, who is also chief scientific officer of the Cardiovascular Research Foundation Clinical Trials Center, co-director of Transcatheter Cardiovascular Therapeutics and associate medical editor of Cardiology Today’s Intervention, and colleagues analyzed the effect of symptom onset-to-balloon time and DBT on myocardial reperfusion in 2,056 patients from HORIZONS-AMI who underwent PCI after STEMI.
The outcomes of interest were resolution of ST-segment elevation and myocardial blush grade. Patients were stratified by symptom onset-to-balloon time 2 hours or less, more than 2 to 4 hours or more than 4 hours, and door-to-balloon time 1 hour or less, more than 1 hour to 1.5 hours and more than two hours. Current guidelines state that DBT should be 1.5 hours or less.
Effect on microvascular indicators
Mehran and colleagues found that lack of microvascular perfusion, defined as a myocardial blush grade of 0 or 1, and ST-segment elevation resolution < 30% after primary PCI were more common in patients with longer symptom onset-to-balloon time (P < .001 for all). This was the case regardless of whether a patient had a low (P = .0002 for myocardial blush grade; P < .0001 for ST-segment elevation resolution) or high (P = .0001 for myocardial blush grade; P = .02 for ST-segment elevation resolution) clinical risk profile as defined by TIMI risk score.
When the researchers conducted a multivariable analysis, they determined that independent predictors of lack of microvascular perfusion were symptom onset-to-balloon time (P < .0001), DBT (P < .0001), anterior infarction (P < .0001), reference vessel diameter (P = .005), lesion minimum lumen diameter (P < .0001), hyperlipidemia (P = .03) and current smoking (P = .001).
They found that independent predictors of ST-segment elevation resolution < 30% were symptom onset-to-balloon time (P = .007), anterior infarction (P < .0001) and history of renal insufficiency (P = .0002).
Patients with myocardial blush grade 0 or 1 and ST-segment elevation resolution < 30% had increased risk for 3-year mortality, and myocardial blush grade 0 or 1 was an independent predictor for it, “which highlights the adverse clinical effect of a closed microcirculation in STEMI patients,” the researchers wrote.
Take-home messages
In a related editorial, Michael A. Kutcher, MD, from the section of cardiovascular medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina, wrote that “the basic findings of a delay in reperfusion equating to poorer outcomes is not a surprise. The exception in this study is the attention to [symptom onset-to-balloon time], which is a stronger predictor of microvascular injury when [primary] PCI is delayed regardless of DBT.”
He wrote that take-home messages from the study include symptom onset-to-balloon time > 2 hours and especially > 4 hours is a risk factor for morbidity and mortality, quick DBT can make a difference if symptom onset-to-balloon time is less than 2 hours, and impaired myocardial perfusion is a strong predictor of mortality at 3 years. – by Erik Swain
Disclosure: Mehran reports financial ties with Abbott Vascular, AstraZeneca, Bayer, Boston Scientific, Bristol-Myers Squibb/Sanofi, Covidien, CSL Behring, Eli Lilly/Daiichi Sankyo, Endothelix, Janssen Pharmaceuticals, Maya Medical, Merck, Osprey Medical, Regado Biosciences, Sanofi, Stentys, The Medicines Company and Watermark Research Partners. See the full study for a list of the other researchers’ relevant financial disclosures. Kutcher reports consulting for Medicure Pharma.