From the Journals

Refined heart rate cutoffs may improve prognostic value of acute PE scoring systems


 

FROM CHEST

In patients with acute pulmonary embolism, using cutoff values other than 110 beats per minute might improve the prognostic value of heart rate at admission, a recent observational study suggests.

Dr. Albert J. Polito Courtesy of Mercy Medical Center

Dr. Albert J. Polito

For identifying low-risk patients, a cutoff of 80 bpm increased the sensitivity of the simplified Pulmonary Embolism Severity Index (sPESI) from about 94% to nearly 99% among nonhypotensive patients with acute symptomatic pulmonary embolism (PE), according to results of the large, registry-based study.

Similarly, using a 140-bpm cutoff increased the specificity of the Bova score for identifying intermediate-high–risk patients from about 93% to 98% in the study, which was recently published in the journal CHEST.

“Although standard dichotomization of HR [i.e., HR less than 110 vs. greater than 110 bpm] may be useful for guideline recommendations, our results will allow for more accuracy regarding clinical decision-making,” wrote lead author Ana Jaureguízar, MD, of the University of Alcalá in Madrid, on behalf of the RIETE (Registro Informatizado de la Enfermedad TromboEmbólica) investigators.

Intuitive findings inform future research

These observational findings are intuitive and do at least have the potential to inform the design of future randomized clinical trials, according to Albert J. Polito, MD, chief of the division of pulmonary medicine and medical director for the lung center at Mercy Medical Center in Baltimore.

“In medicine, there is a spectrum of risk,” Dr. Polito said in an interview. “While we love our cutoffs, which in this case has traditionally always been that 110 beats per minute for heart rate, it makes sense that there would be some range of risks of bad outcomes.”

Building on the observations of the present study, subsequent prospective randomized studies could potentially aim to determine, for example, when thrombolytic therapy should be considered in nonhypotensive patients with acute PE and higher heart rates.

“It would not be easy to design, but it’s a straightforward question to ask whether patients with the highest heart rates are the ones who potentially might benefit the most from thrombolytic therapy,” Dr. Polito said.

Value of alternative HR cutoffs

Heart rate is a simple and easily available vital sign that is clearly linked to prognosis in patients with pulmonary embolism, authors of the RIETE registry study say in their report. Accordingly, a heart rate threshold of 110 bpm has made its way into scoring systems that seek to identify low-risk patients, such as the sPESI, and those focused on identifying higher-risk patients, such as the Bova score.

However, it has not been clear whether alternative HR cutoffs would improve upon the 110-bpm threshold, they added. At the low-risk end, more accurate scoring systems could optimize the selection of patients for home treatment, while at the intermediate-high–risk end, they could better select patients for close monitoring or advanced PE treatments.

Better granularity on heart rate risks?

To better define the prognostic value of different heart rate thresholds, investigators analyzed data from RIETE, a large, ongoing, multinational prospective registry including patients with objectively confirmed acute venous thromboembolism.

For 44,331 consecutive nonhypotensive symptomatic PEs, the overall rate of 30-day all-cause mortality was 5.1%, and the 30-day PE-related mortality was 1.9%, the authors report.

Significantly poorer outcomes were seen in patients with higher heart rates as compared to patients in the 80-99 bpm range, they also found. As compared to that reference range, odds ratios for 30-day all-cause death ranged from 1.5 for heart rates of 100-109, up to 2.4 for those with heart rates of 140 bpm or greater.

Likewise, patients with higher heart rates had a 1.7- to 2.4-fold greater risk of 30-day PE-related death as compared to the 80- to 99-bpm reference range, while patients with lower heart rates had lesser risk, the data published in CHEST show.

Toward refinement of prognostic scoring

Next, investigators sought to refine the prognostic scoring systems for low-risk PE (sPESI) and intermediate-high–risk PE (Bova).

For sPESI, they found that dropping the cutoff value from 110 to 100 bpm increased the sensitivity of the score from 93.4% to 95.3%. Going down even further to 80 bpm increased sensitivity to 98.8%, according to the report.

By going down from 110 to 80 bpm, the proportion of patients defined as low-risk dropped from 35% to 12%, according to the investigators.

For the Bova score, increasing the cutoff value from 110 to 120 bpm likewise increased specificity from 93.2% to 95%, while going up even further to 140 bpm increased specificity to 98.0%, the report shows.

In sensitivity analyses, the findings were not impacted by excluding younger patients, those who received reperfusion therapies, or those with atrial fibrillation, according to the study findings.

Potential implications for clinical practice

Taken together, these findings could serve as a resource to inform discussions regarding PE management that include whether home therapy or use of thrombolytic therapy is appropriate, investigators said in their report.

“For instance, among low-risk sPESI patients, those with borderline tachycardia [i.e., a heart rate between 100-109 bpm] might benefit from initial hospital observation for trending,” they wrote.

Dr. Jaureguízar reported no disclosures. One coinvestigator reported funding support from the Institute of Health Carlos III (ISCIII) and the European Development Regional Fund (ERDF). One coinvestigator reported consulting in litigation involving two models of inferior vena cava filters.

Dr. Polito reported no disclosures.

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