In STEMI PCI, Symptom-to-Balloon Time Is What Counts

Delays in seeking care for ST-segment elevation MI (STEMI) appeared more important than contemporary in-hospital delays for coronary angioplasty, a study suggested.

Whereas time from hospital arrival to angioplasty balloon inflation was not a significant predictor of larger infarct size after percutaneous coronary intervention (PCI), symptom-to-balloon time (SBT) was.

Compared with infarcts seen after a SBT of no more than 2 hours, they took up 2.0% more left ventricular mass (95% CI 0.4-3.5) if the time was 2 to 4 hours and 4.4% more if the time was even longer (95% CI 2.7-6.1).

Similarly, SBT was an independent predictor of greater microvascular obstruction (MVO) post-PCI, unlike door-to-balloon time (DBT), according to Gregg Stone, MD, of Mount Sinai Medical Center in New York City and the Cardiovascular Research Foundation, and colleagues reporting in Circulation: Cardiovascular Interventions.

While underpowered for clinical outcomes, the study also showed a stronger relationship of SBT vs DBT for the composite of death or heart failure hospitalization, which is as would be expected since infarct size and MVO after reperfusion therapy are both independent predictors of subsequent heart failure and mortality, Stone’s group added.

SBT accounts for pre-hospital delays but may be subject to imprecise patient perception and recollection as to the time of symptom onset in STEMI.

Accordingly, DBT has become the preferred performance metric for PCI in STEMI. U.S. guidelines recommend that DBTs not exceed 90 minutes, whereas European ones push the goal even further to 60 minutes.

Collective efforts to achieve this mean that DBTs are now nearly always under 90 minutes in contemporary angioplasty practice, according to Stone and colleagues.

“While we shouldn’t become complacent and relax our current standards of rapidly performing PCI as soon as possible after the patient reaches the hospital, this study suggests that major efforts to further shorten DBTs by 10 or 20 minutes might not translate to better PCI outcomes,” Stone said in a press release.

“Our analysis indicates the more important and meaningful focus should be to shorten the delays from symptom onset to arrival at hospitals that can perform PCI. We must emphasize efforts to increase public awareness of heart attack symptoms and shorten the time it takes for patients to access emergency care,” Stone urged.

In the study, STEMI patients with longer SBTs in their study tended to be older and more likely women. They also more commonly presented with hypertension, diabetes, and left circumflex artery as the culprit vessel.

The investigators had pooled ten PCI trials that included a total of 3,115 STEMI patients with sufficient imaging data. Infarct size had been assessed a median 5 days after PCI by SPECT or cardiac MRI. Microvascular obstruction was assessed with cardiac MRI.

Median SBT and DBT were 185 minutes and 46 minutes, respectively.

Trials included in the study were INFUSE-AMI, APEX, CRISP, AIDA, LIPSIA-N-ACC, LIPSIA-STEMI, LIPSIA-ABCIX, EMERALD, AMIHOT-II, and IMMEDIATE. There was some heterogeneity in the study populations and endpoint definitions among these trials, investigators acknowledged.

Chief among the limitations of the study was that the authors did not have sufficient information to adjust for intensity of chest pain and other clinical symptoms of STEMI, time to first medical contact, or the presence and extent of coronary collaterals.

Even so, the findings are important and especially relevant today, according to American Heart Association President Mitchell Elkind, MD, MS, of New York-Presbyterian/Columbia University Irving Medical Center in New York City.

“During the peaks of the COVID-19 pandemic, hospitals are reporting fewer people coming into the emergency room for heart attack and stroke symptoms — indicating people aren’t calling 911, or they are delaying or avoiding critical care,” Elkind said in the press release.

“These new findings emphasize just how crucial it is to call 911 at the first sign of a heart attack or stroke – because getting quick treatment can be the difference between life and death,” he said. “As we have been urging even during the COVID-19 pandemic, don’t die of doubt. Call 911 as soon as possible.”