After cardiac arrest, certain patients with suspected ST-segment elevation myocardial infarction (STEMI) are denied emergent angiography due to adverse clinical factors or the judgment that intervention would be futile, according to a registry study published online February 7, 2013, ahead of print in the American Journal of Cardiology. The results show that such patients face a markedly higher risk of early mortality, regardless of comorbidities or illness severity.

Investigators led by Stephen W. Waldo, MD, of the University of California, San Francisco (San Francisco, CA), looked at 110 patients who were referred for emergent angiography for a possible STEMI after cardiac arrest. Of these, 26 patients were denied the procedure because it was deemed clinically unnecessary (69%) or futile (27%), or for undocumented (4%) reasons.

Factors Predicting Angiography Denial

In multivariate analysis, certain demographic and clinical characteristics emerged as predictors of denial of angiography (table 1).

Table 1. Predictors of Denial of Angiography

 
Overall median follow-up was 8 days, while median follow-up for patients who survived to hospital discharge was 184 days. Length of hospital stay was longer and mortality substantially higher among those who were denied angiography, especially within the first day. The mortality finding persisted after adjustment for severity of illness (HR 2.29; 95% CI 1.19-4.41; table 2).

Table 2. In-Hospital Outcomes by Performance or Denial of Emergent Angiography

Even after exclusion of patients denied catheterization due to perceived futility, those who did not receive emergent angiography experienced a trend toward higher mortality (adjusted HR 1.51; 95% CI 0.73-3.11).

Among the 84 patients who did receive angiography, culprit lesions necessitating PCI were found in 72% (n = 60). However, PCI did not reduce mortality risk compared with no intervention (HR 0.79; 95% CI 0.41-1.55).

Use of emergent angiography and intervention in patients after cardiac arrest remains controversial, the authors write, noting that current guidelines suggest that performance of catheterization may be left to the discretion of treating physicians. “Our findings highlight the continued challenges in selecting the appropriate patients to undergo emergent coronary angiography after cardiac arrest,” they observe.

Angiography Decision ‘Incredibly Complex’

In an e-mail communication with TCTMD, Dr. Waldo called a decision about whether to perform emergent angiography after cardiac arrest “incredibly complex.” The strategy may be recommended if the “prior probability of coronary disease and thus the potential benefit from intervention exceeds the probability of the risks,” he wrote, but complicating this calculus is the fact that previous research suggests the prevalence of epicardial thrombi in this population varies considerably.

“The [study] demonstrates that other clinical characteristics also play a conscious or subconscious role in calculating the potential benefit in this patient population,” Dr. Waldo noted. “But no one clinical factor should necessarily encourage or discourage a diagnostic test.  Rather, this information should be integrated into the overall clinical presentation.” Moreover, although each factor appears to be legitimate, arguably they are not predictors of epicardial thrombus and thus “we should reevaluate how we determine who may benefit from emergent angiography.”

Previous data have suggested that PCI is associated with improved outcomes among patients with cardiac arrest, Dr. Waldo pointed out, adding that the present study showed the same trend but was not statistically powered to confirm this benefit. “Perhaps patients with a cardiac arrest induced by an epicardial thrombus have an improved prognosis simply because they have an identifiable and correctable etiology for their arrest,” he said. “Angiography plus PCI is clearly beneficial for this population, while it would be unlikely to provide significant benefit for those with a cardiac arrest not precipitated by an occluded coronary artery.”

Overall, patients denied emergent angiography after cardiac arrest “represent a unique population with increased mortality rates,” Dr. Waldo commented. “Further studies should evaluate the clinical decision process that leads to denial of angiography as well as its potential benefit in this understudied population.”

Although larger, randomized trials would help define emergent angiography’s role in this group, significant logistical and financial challenges make them unlikely in the foreseeable future, he concluded.

Study Details

Patients with cardiac arrest who did not undergo emergent angiography were older (P < 0.01) and more often female (P < 0.03). Pulseless electrical activity was the predominant initial arrest rhythm compared with ventricular fibrillation for those who underwent the procedure (P < 0.03). Symptoms associated with ischemia such as chest pain and dyspnea were less common in patients denied angiography (P < 0.01). They also had lower heart and respiratory rates (both P < 0.01) and lower systolic blood pressures (P < 0.02) on presentation, leading to numerically greater use of mechanical ventilation and vasopressors. Moreover, ECG evidence of left ventricular hypertrophy was more common in patients who did not proceed to catheterization (P < 0.01).

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