Women Stand to Gain the Most From Standardized STEMI Protocols

Implementation of a comprehensive STEMI protocol, one intended to improve the consistency of treatment, can reduce the historic disparities in clinical outcomes and care processes between men and women, according to results from a new study

Five years after the protocol was put in place, there were no sex-related differences in the risk of in-hospital major adverse cardiovascular and cerebrovascular events or mortality, an equalization that investigators attribute to consistent use of guideline-directed medical therapy (GDMT), transradial access, and improved door-to-balloon (D2B) times. 

“If you really focus strongly on introducing a consistent process for your STEMI patient, then you’re going to reduce care variability, which disproportionately appears to help women,” senior investigator Umesh Khot, MD (Cleveland Clinic, OH), told TCTMD.

Nationally and internationally, there is well-documented evidence showing that rates of in-hospital adverse events, de novo heart failure, and mortality from STEMI are significantly higher in female patients. Likewise, there is evidence showing that women receive less GDMT and have slower D2B times. The differences are so well established that the European Society of Cardiology and American Heart Association have called the need to reduce disparities in STEMI between men and women a public health priority, said Khot.

Janet Wei, MD (Cedars-Sinai Medical Center, Los Angeles, CA), who previously showed improvements in women’s care and outcomes after the implementation of a standardized protocol and organized transfer system in Minnesota, said the new study was reassuring in that investigators showed improvements in D2B times, as well as other factors important to better outcomes.

“In the past 5 years, there have been advances in having more systems-wide protocols in place,” Wei told TCTMD, citing the work of Timothy Henry, MD (The Christ Hospital, Cincinnati, OH), and others. In Los Angeles County, for example, there has been a large effort to develop and implement a standardized STEMI protocol. “Work done in this field shows that we do need these types of protocols in place, particularly in areas where there is interhospital transfer because I think that can often be the source of delay,” she stressed.

STEMI Protocol Sustainable

For the study, published last month in the European Heart Journal Open, investigators led by Chetan Huded, MD (Saint Luke’s Mid America Heart Institute, Kansas City, MO), focused on the 5-year follow-up of the STEMI protocol instituted at the Cleveland Clinic and a network of hospitals in northeastern Ohio. In 2018, researchers reported that the protocol could reduce sex-related differences in outcomes and processes of care, but the latest analysis focused on its long-term sustainability. The STEMI protocol includes the following:

• Catheterization lab activation from the emergency department (ED) without delay for a cardiology consult;
   
• Use of the STEMI checklists to standardize early triage and management of patients, including use of GDMT (prerevascularization use of aspirin, a P2Y12 inhibitor, and anticoagulant);
   
• Immediate transfer to an available cath lab;
   
• Use of a radial-first approach to PCI

“Basically, it [involves] four key steps we hardwired throughout our entire healthcare system,” said Khot. To ensure timely treatment, the patient is immediately shipped from the ED without waiting to hear if the cath lab is ready. Most hospitals, noted Khot, require an approval process before teams can start moving the patient. He added that while transradial PCI is more mainstream today, that wasn’t quite the situation in 2014, especially in the US.

To assess how well the protocol worked, researchers compared outcomes with a historic control group. The study population consisted of 1,833 patients treated with primary PCI, of whom 723 patients (32.2% female) were controls treated before the implementation of the STEMI protocol and 1,110 (32.5% female) treated after it was launched.

In the control arm, GDMT prior to arterial sheath insertion was used significantly less in women than in men (68.1% vs 77.1%; P = 0.03) and D2B times were significantly longer (112 vs 104 minutes; P = 0.02). Transradial access was infrequent in both men and women (19.0% men vs 17.6% women; P = 0.73). After the implementation of the STEMI protocol, use of GDMT was similar in men and women (87.2% vs 86.4%, respectively; P = 0.81) as were D2B times (85 vs 89 minutes; P = 0.06). Transradial access increased substantially in both men and women, although it was still used less in women treated during the protocol period (77.6% vs 71.2%; P = 0.03).

Rates of mortality, MACCE, stroke, and bleeding were all significantly higher in women treated before the introduction of the STEMI protocol, but outcomes equalized after the protocol was instituted. Mortality, MACCE (death, reinfarction, stroke, and cardiogenic shock), and stroke did not differ between men and women, although rates of bleeding were higher in female patients (11.1% vs 7.2%; P = 0.03). This translated into a higher rate of net adverse clinical events (19.4% vs 14.8%; P = 0.05). Researchers suspect the higher bleeding risk might be related to greater use of transfemoral PCI.

Wei said she’d be interested to learn if women across all age ranges benefited from the STEMI protocol. In their previous study, the unadjusted rate of in-hospital mortality was higher among women, but the difference disappeared once the analysis was adjusted for age.

“One thing I think we need to highlight regarding the goals of understanding sex differences in MI is that there might be age-related differences,” she said.

Younger women with STEMI might be more vulnerable to worse outcomes because of underlying differences in the etiology of MI, which would alter how they would be treated, said Wei. For example, they may be more likely to have STEMI in the absence of obstructive CAD or due to mechanisms separate from plaque rupture, such as spontaneous coronary artery dissection or vasospasm. In their previous study, she added, women received prerevascularization GDMT at the same frequency as men but were less likely to receive statins or antiplatelet therapy at discharge.

Another aspect of the Cleveland Clinic program to highlight, said Wei, is the greater inclusion of Black patients (24% Black men and 30.8% Black women) than they achieved in their study, where 95% of STEMI participants were white. Given important issues around race and access to care, the inclusion of a larger proportion of non-white patients is important, she said.

Shifting the Primary Focus

To TCTMD, Khot said that when the STEMI protocol was launched, the primary focus had been on accelerating D2B times, but the emphasis now is on eliminating variability in care, which is a “sea change” in terms of thinking about STEMI. He pointed out that the reduction in clinical outcomes—observed with the protocol in both men and women —can’t solely be accounted for by the reduction in D2B time but would likely be attributable to several improved processes of care, including greater use of transradial PCI and GDMT. 

The STEMI protocol, said Khot, is easily replicable to other institutions and simply requires an organizational focus on consistency.

“If you have an existing STEMI system, it doesn’t require you to add new equipment or spend a lot of money,” he said. “It really requires a ‘rethink’ in terms of how you’re providing that care so you’re doing it in a consistent fashion. I think this can be done anywhere STEMI care is provided. These four steps are fairly easily duplicated.”