Israel Medical Association Journal

Abstract

Background: Heart rate variability (HRV) analysis has been shown to be a predictor of sudden cardiac death and all-cause mortality in patients with cardiac disease.

Objectives: To examine whether newer HRV analysis algorithms, as used by the HeartTrends device, are superior to exercise stress testing (EST) for the detection of myocardial ischemia in patients without known coronary artery disease (CAD).

Methods: We present pilot data of the first 100 subjects enrolled in a clinical trial designed to evaluate the yield of short-term (1 hour) HRV testing for the detection of myocardial ischemia. The study population comprised subjects without known CAD referred to a tertiary medical center for EST with single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI). All patients underwent a 1 hour electrocardiographic acquisition for HRV analysis with a HeartTrends device prior to EST with MPI. Sensitivity, specificity, and positive and negative predictive values (PPV and NPV, respectively) were calculated for EST and HRV analysis, using MPI as the gold standard for the non-invasive detection of myocardial ischemia.

Results: In this cohort 15% had a pathologic MPI result. HRV analysis showed superior sensitivity (85%), PPV (50%) and NPV (97%) as compared to standard EST (53%, 42%, 90%, respectively), while the specificity of the two tests was similar (86% and 85%, respectively). The close agreement between HRV and MPI was even more pronounced among patients > 65 years of age.

Conclusions: Our pilot data suggest that the diagnostic yield of the novel HeartTrends HRV algorithm is superior to conventional EST for the non-invasive detection of myocardial ischemia.

Background: Many patients present to the emergency department with chest pain. While in most of them chest pain represents a benign complaint, in some patients it underlies a life-threatening illness.

Objectives: To assess the routine evaluation of patients presenting to the ED[1] with acute chest pain via the utilization of a cardiologist-based chest pain unit using different non-invasive imaging modalities.

Methods: We evaluated the records of 1055 consecutive patients who presented to the ED with complaints of chest pain and were admitted to the CPU[2]. After an observation period and according to the decision of the attending cardiologist, patients underwent myocardial perfusion scintigraphy, multidetector computed tomography, or stress echocardiography.

Results: The CPU attending cardiologist did not prescribe non-invasive evaluation for 108 of the 1055 patients, who were either admitted (58 patients) or discharged (50 patients) after an observation period. Of those remaining, 445 patients underwent MDCT[3], 444 MPS[4], and 58 stress echocardiography. Altogether, 907 patients (86%) were discharged from the CPU. During an average period of 236 ± 223 days, 25 patients (3.1%) were readmitted due to chest pain of suspected cardiac origin, and only 8 patients (0.9%) suffered a major adverse cardiovascular event.

Conclusions: Utilization of the CPU enabled a rapid and thorough evaluation of the patients’ primary complaint, thereby reducing hospitalization costs and occupancy on the one hand and avoiding misdiagnosis in discharged patients on the other.
 

[1] ED = emergency department

[2] CPU = chest pain unit

[3] MDCT = multidetector computed tomography

[4] MPS = myocardial perfusion scintigraphy