Time between STEMI symptom onset, procedure appears to be crucial in PCI outcomes
Time from MI symptom onset to PCI may be a stronger predictor of infarct size and microvascular obstruction than door-to-balloon time in patients with STEMI, researchers reported.
“We found that the total time to reperfusion was strongly related to infarct size and clinical outcomes, whereas door-to-balloon time was not,” Gregg W. Stone, MD, director of academic affairs for the Mount Sinai Heart Health System and professor of medicine and population health sciences and policy at the Zena and Michael A. Wiener Cardiovascular Institute at the Icahn School of Medicine at Mount Sinai, told Healio. “The implications are that given contemporary short door-to-balloon times, delays to hospital arrival are now a much more important predictor of infarct size and adverse clinical outcomes.”
For the analysis, researchers used individual patient data from 3,115 patients hospitalized with STEMI who underwent primary PCI in 10 randomized trials to evaluate the effect of door-to-balloon time and symptom-to-balloon time on infarct size and microvascular obstruction. Infarct size was assessed within 1 month after randomization; microvascular obstruction was assessed by cardiac MRI; symptom-to-balloon time was categorized as short ( 2 hours), intermediate (2 to 4 hours) or long (> 4 hours); and door-to-balloon time was categorized as short ( 45 minutes), intermediate (45 to 90 minutes) or long (> 90 minutes).
‘Time is muscle’
“For several decades, cardiologists have been taught ‘time is muscle,’ meaning the longer the time from the infarct onset until infarct artery recanalization, the greater the extent of heart muscle damage and the higher the mortality,” Stone said in an interview. “The two components of ‘time’ is how long it takes the patient to get to the hospital from the onset of symptoms, and then after hospital arrival, how long it takes the hospital to diagnose the infarct and then transfer the patient to the cath lab and open the artery.”
Researchers observed a stepwise increase in infarct size for intermediate vs. short symptom-to-balloon time (adjusted difference, 2%; 95% CI, 0.4-3.5) and long vs. short symptom-to-balloon time (adjusted difference, 4.4%; 95% CI, 2.7-6.1) for STEMI.
However, intermediate vs. short door-to-balloon time (adjusted difference, 0.4%; 95% CI, –1.2 to 1.9) and long vs. short door-to-balloon time (adjusted difference, –0.1%; 95% CI –1 to 3) did not affect infarct size.
In addition, microvascular obstruction was greater in patients with long compared with short symptom-to-balloon time (adjusted difference, 0.9%; 95% CI, 0.3-1.4) for STEMI.
Researchers observed no difference in microvascular obstruction between patients with intermediate vs. short symptom-to-balloon time (adjusted difference, 0.1%; 95% CI, –0.4 to 0.6).
Moreover, there was no difference in microvascular obstruction for any category of door-to-balloon time for STEMI.
Recognizing MI signs and symptoms
“Further shortening door-to-balloon times is unlikely to further improve outcomes,” Stone told Healio. “Rather, we need to redouble our efforts to educate patients to recognize the signs and symptoms of a heart attack and activate 911 sooner to ensure faster hospital arrivals. This is especially important in the COVID-19 era, given patients having greater reticence to come to hospitals, leading to larger heart attacks and higher rates of mortality and HF.”
For more information:
Gregg W. Stone, MD, can be reached at gregg.stone@mountsinai.org; Twitter: @greggwstone.
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