Heart Rate and Mortality in Acute Pulmonary Embolism

Management of the non-hypotensive acute PE patient can prove challenging as there are multiple therapeutic options available including anticoagulation only, advanced therapies including catheter directed interventions (thrombolysis or embolectomy), surgical pulmonary embolectomy, and systemic thrombolysis. Risk stratification is important in helping to determine which patients may benefit from treatment with anticoagulation versus more advanced therapies. There are various scoring systems and clinical findings that can assist in risk stratification of normotensive PE patients including the BOVA score, PESI/sPESI score, European Society of Cardiology Guidelines on Acute PE, and echocardiographic measurements of right ventricle function and output. A standard dichotomized heart rate (HR) level of 110 beats per minute (bpm) is incorporated into the commonly used BOVA and PESI scores and has been used for determining the presence or absence of tachycardia in patients with PE.

The study by Jaureguízar A et al evaluated whether there is an association between outcome and HR levels at presentation in patients with acute PE. The study demonstrated that in a large cohort of normotensive patients presenting with acute PE, there was a positive association with increasing HR levels at the time of admission and both all cause and PE related mortality, with the highest mortality seen in patients with HR levels greater than 140 bpm and the lowest mortality in patients with HR levels less than 60 bpm. In addition, the study evaluated the impact of modifying the HR level cutoff in the sPESI and BOVA scores and found that different HR cutoffs could potentially improve the scoring systems. For example, lowering the HR threshold for the sPESI score increased its sensitivity whereas increasing the HR threshold for BOVA increased its specificity. It is unclear how the HR levels in patients taking AV nodal blocking agents or in patients who have underlying AV nodal disease or significant arrhythmias impacts the use of HR as a prognostication tool. The study assessed admission HR but it remains unclear whether trends in HR or ratios of HR to blood pressure such as shock index would serve as a better tool for prognostication.

The admission HR may be associated with all cause and PE related mortality and thereby potentially help to identify patients with PE that are at a low or higher risk of mortality. However, risk stratification for PE and optimal treatment is based on multiple clinical findings specific to the presenting patient such as severity of right ventricular dysfunction, elevated cardiac biomarkers, elevated lactate, underlying cardiopulmonary reserve, and comorbid conditions, to name a few. Overall, assessment of HR is an affordable, widely accessible, and reliable tool that may help rapidly identify patients that are at an increased risk of mortality from PE and those that may benefit from additional evaluation and intervention.