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Only about 1 in 4 patients with acute myocardial infarction (MI) and multivessel disease complicated by cardiogenic shock undergoes immediate percutaneous coronary intervention (PCI) of all significant lesions, as recommended by the current European Society of Cardiology (ESC) guidelines, according to a German registry study published online August 20, 2014, ahead of print in EuroIntervention. However, the majority, who receive revascularization of the culprit vessel alone, are less likely to die during the index hospitalization.

The authors suggest that based on these and other data, PCI should be limited to the infarct-related artery except in selected cases of prolonged hemodynamic instability after successful initial revascularization. But Sorin J. Brener, MD, of Weill Cornell Medical College (New York, NY), argued in a telephone interview with TCTMD that failure to account for the hemodynamic impact of the initial intervention invalidates comparison of the treatment groups.

 More Procedural Complications, Adverse Events with Multivessel PCI 

Not surprisingly, contrast volume and fluoroscopy time were greater with multivessel compared with culprit-vessel-only PCI (both P < .001) and some procedural complications were numerically more frequent, including CPR (15.0% vs 12.5%) and acute vessel closure (5.8% vs 2.3%).

During index hospitalization, culprit-vessel PCI patients were more likely to undergo additional revascularization (PCI or CABG) than were multivessel PCI patients (9.2% vs 3.3%). Rates of mortality and dialysis were higher in the multivessel group, while rates of reinfarction, stroke, and bleeding were low and comparable between the groups (table 1).

Table 1. Adverse Events During Index Hospitalization

Multivariable analysis identified independent predictors of in-hospital mortality:

• Multivessel PCI (adjusted OR 1.50)
• Age, per 10-year increase (adjusted OR 1.2)
• Renal failure (adjusted OR 1.56)
• Diabetes (adjusted OR 1.50)
• Triple-vessel disease (adjusted OR 1.38)

Pros and Cons of Multivessel Strategy

Unlike the ESC guidelines, ACC/AHA guidelines are neutral regarding the choice of multivessel vs culprit-vessel primary PCI in cardiogenic shock patients, the authors observe, noting that evidence for the former approach is slim and includes no randomized data.

They acknowledge, however, that the multivessel approach has some theoretical advantages. For example, it may:

• Limit infarct size and preserve LV function
• Prevent ischemia in the non-infarct-related vessels, which could obviate the need for future procedures and reduce recurrent events
• Reduce overall hospital stay and total cost of care

On the other hand, they point out, the prolonged multivessel procedure may increase:

• Contrast use and thus the risk of contrast-induced nephropathy and LV volume overload
• Risk of stent thrombosis in the non-culprit lesions
• Need for subsequent procedures due to restenosis or acute stent thrombosis
• Risk of periprocedural MI 

Most registry reports have found worse outcomes following multivessel PCI in STEMI patients with shock, the investigators say, although the recent randomized PRAMI and CvLPRIT trials favored intervention in all significant lesions among STEMI patients without shock.

Ultimately, only a large randomized study can delineate the proper role of multivessel PCI in this population, Dr. Zeymer and colleagues say, adding that the answer should be forthcoming from the ongoing CULPRIT-SHOCK trial. 

Lack of Data on Persistence of Shock Muddies Comparison

However, Dr. Brener described the paper as unhelpful and potentially misleading.

He explained that in these patients the PCI strategy depends largely on whether shock is relieved by the initial, culprit-vessel revascularization. Often, myocardial territories adjacent to the culprit vessel compensate for reduced cardiac output until the infarct-related artery can be opened. But if the vessels supplying the adjacent myocardium are themselves severely stenotic, making it ischemic, compensation may be compromised, leaving the patient in shock. 

In short, he said, “stabilization determines whether you should go after those other [non-culprit] lesions. If the patient is stabilized, you should probably not [revascularize] them. That’s what the guidelines recommend.”

Unfortunately, the investigators do not say what happened after the infarct-related vessels were opened, he pointed out, adding that without propensity matching to minimize this key difference between the treatment groups, comparison is meaningless.

Any excess risk of complications from additional stenting is largely irrelevant for patients who remain in hemodynamic crisis after culprit-vessel revascularization, Dr. Brener observed, adding that in this situation PCI should be as complete as possible.

The main reason operators may not open non-culprit arteries in this situation is that they contain total occlusions, he said, but the paper does not report the frequency of such occlusions. Another important unreported variable affecting the multivessel PCI decision is the status of myocardium downstream from a stenosis, he added. PCI is warranted only if the tissue is still viable.

Dr. Brener said the authors could have simply reported that a conservative, culprit-vessel-only approach was adopted in almost three-quarters of patients and acknowledged that there is insufficient granularity in the registry data to know why.

The most likely answer, he suggested, is that the initial PCI stabilized many patients hemodynamically. “If that is the case, then we’re comparing a very sick group of people with a healthier group, and that makes no sense,” he concluded. 

Source: 
Zeymer U, Hochadel M, Thiele H, et al. Immediate multivessel percutaneous coronary intervention versus culprit lesion intervention in patients with acute myocardial infarction complicated by cardiogenic shock: results of the ALKK-PCI registry. EuroIntervention 2014;Epub ahead of print.

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