PCI for Cardiogenic Shock: Mortality Has Increased, but So Has Patient Risk

Even with advances in the care of cardiogenic shock patients undergoing PCI, mortality rates have climbed over the past decade, according to new data from a national database.

However, this trend may be due to the fact that “we are increasingly managing much sicker patients invasively (with greater experience and better support devices), many of whom would not have been considered for PCI referral a decade ago,” study author Siddharth Wayangankar, MD, MPH, of the Cleveland Clinic (Cleveland, OH), and colleagues write.

They looked at 56,497 patients from the CathPCI Registry who underwent PCI for acute MI complicated by cardiogenic shock between January 2005 and December 2013.

Patients treated at the end of the study period were generally higher-risk than those treated at the beginning—they were more likely to have diabetes, hypertension, dyslipidemia, previous PCI, and undergo dialysis but less likely to have chronic lung disease, renal dysfunction, peripheral vascular disease, or heart failure within 2 weeks.

Decreasing use of intra-aortic balloon pumps (IABPs; 49.5% vs 44.9%; P < .01) and DES (65% vs 46%; P < .01) was seen over the study period, while bivalirudin use increased (12.6% vs 45.6%; P < .001). Multi-lesion PCI also declined from 31.5% to 25.7% (P < .01). In STEMI patients with delayed PCI, more than one-third of delays were due to cardiac arrest or failure to intubate.

The decrease in IABPs is “probably suggestive of the fact that most operators do not prefer to use IABP preemptively to first stabilize the patient,” Wayangankar and colleagues write, adding that this could be “partially driven by the pressure to comply with [door-to-balloon time] performance measures” and also stem from the idea that treating the culprit vessel would improve hemodynamics, thereby “obviating the need for additional support.”

The decrease in multi-lesion PCI is discrepant with the fact that most of the patients in the study cohort had multivessel disease, the incidence of which has been increasing over time. Real-world practice seems to reflect the notion that “most operators are reluctant” to perform multivessel stenting despite current guideline recommendations, the authors say, but the benefit of immediate complete PCI—as shown in the PRAMI and CVLPRIT trials—“may be more pronounced in high-risk unstable patients like [those with acute MI and cardiogenic shock].”

‘Disconcerting’ Outcomes

Overall complications decreased significantly over the study period but still occurred in about one-third of cases. Successful PCI rates increased “marginally,” according to the authors, “but plateaued at 85% of the cases.” Yet in-hospital mortality rose from 27.6% in 2005-2006 to 30.6% in 2001-2013 (P < .01), with about one-fifth of deaths occurring in the cath lab. The increase in mortality, as well as the decreases in renal failure and bleeding, remained after multivariate adjustment.

The improvements in renal failure and bleeding are “a reflection of operators being cognizant about [the] impact of bleeding on procedural outcomes, and their keenness to [routinely] incorporate bleeding avoidance strategies” like radial access and bivalirudin use, the authors say. But the “disconcerting” rise in mortality raises questions about the optimal timing of treatment for this high-risk population.

Given the rising complexity of patients managed invasively, however, “these rates probably represent the best that can be achieved in this high-risk subset of [acute MI] patients,” Wayangankar and colleagues write.

Interestingly, the authors note that women, those with a BMI < 30 Kg/mm², and patients with a history of PCI seem to be protected from in-hospital mortality. This was surprising, Wayangankar told TCTMD, because prior studies have shown that women typically fare worse than men with regard to mortality. As for those with a history of PCI, he said, it is likely that they were already on cardioprotective medications and may have benefitted from ischemic preconditioning.

Recommendations for the Future

In an accompanying editorial, Tanveer Rab, MD, of Emory University Hospital (Atlanta, GA), called the trend toward increasing mortality “disturbing.” He attributes it to the growing number of patients with cardiogenic shock in the registry over time and the parallel uptick in use of bivalirudin.

“Recent studies have challenged the efficacy of bivalirudin vs heparin. One could, therefore, speculate that without adequate clopidogrel pretreatment or absorption, ischemic events and mortality increased with bivalirudin use,” he writes, advising that operators discontinue use of the novel anticoagulant in this population and rely on heparin instead. Use of GPIs, however, should be increased, Rab suggests.

Listing other recommendations, he focuses on the need for early mechanical circulatory support “to stabilize patients pre-PCI and discourage IABP use.” LV support, Rab says, “provides the interventionalists the time to treat increasingly complex lesions … without further cardiac decompensation and improves survival.”

He also recommends aiming for complete revascularization, switching to radial access, and using second-generation DES as means to improve long-term survival.

“On a positive note,” Rab concludes, the 43% of cases “shifted to” PCI centers performing less than 500 cases annually had “strikingly” lower mortality than those at higher-volume centers. This is surprising, given past observations that lower volume centers have worse outcomes, he said. “A preferential bias for sicker patients being directed to large volume centers could [partly explain this finding], but in general patients are transported to the nearest facility.”

Sources: 
1. Wayangankar SA, Bangalore S, McCoy LA, et al. Temporal trends and outcomes of patients undergoing PCI for cardiogenic shock in the setting of acute myocardial infarction: a report from the CathPCI Registry. J Am Coll Cardiol Interv. 2016;Epub ahead of print.
2. Rab T. Disappointing results, but we must carry on [editorial]. J Am Coll Cardiol Interv. 2016;Epub ahead of print.

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• Cardiogenic Shock Still Tied to High Post-PCI Mortality for ACS Patients
• Culprit-Vessel-Only PCI May Be Better for MI Patients with Multivessel Disease, Cardiogenic Shock
• Multivessel Bests Culprit-Only PCI in STEMI Patients with Shock, Cardiac Arrest