Cardiac stress test findings normal in premotor Parkinson’s disease patients

By Afsaneh Gray, medwireNews Reporter

People who go on to develop Parkinson’s disease (PD) do not perform significantly differently from normal controls on exercise stress testing, an Israeli study has found.

Cardiac sympathetic denervation is known to be an early nonmotor feature of PD, leading previous researchers to investigate whether there are differences in exercise stress testing between people who later develop PD and normal controls, with one paper suggesting that such differences are present.

However, the authors of the current study, published in Movement Disorders, report: “We did not detect significant signs of sympathetic dysfunction during the premotor phase of PD.”

From 16,841 participants who completed a comprehensive screening program called the Executive Screening Survey, including exercise stress testing, lead author Gilad Yahalom (Sheba Medical Center, Ramat Gan) and colleagues identified 28 individuals who subsequently developed PD.

Data were collected on measures including heart rate at rest, at the end of the treadmill test and during recovery, heart rate reserve (the difference between heart rate at rest and at maximal exercise), exercise duration, systolic and diastolic blood pressure, and the presence of any atrial or ventricular arrhythmias during exercise.

The average age at first assessment of the patients who went on to be diagnosed with PD was 64.8 years, compared with 48.9 years in the control group. On average, PD manifested 4.6 years after the first assessment.

When the researchers initially analyzed the results, they found that people in the PD group had a significantly lower heart rate at maximal effort, a lower heart rate reserve, and a higher systolic blood pressure at rest and during recovery compared with controls.

However, after matching the PD group to 56 controls using a propensity score that included age and gender, the team found no significant differences between the groups for any parameters measured.

There was a trend, approaching but not reaching significance, of people in the PD group showing reduced systolic blood pressure at maximal effort and a reduced heart rate reserve.

Yahalom and co-workers cannot identify any clear explanation for why their results differ from those of the previous study. However, they conclude that exercise stress testing “seems to have no diagnostic role in subjects at the premotor phase of PD.”

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