Clinical significance of impaired heart rate recovery after treadmill exercise test in hypertensive patients

ABSTRACT

To evaluate the recovery time after a treadmill exercise ECG test in hypertensive patients and to study the role of beta-blockers on the recovery of the heart rate after exercise. Design: Prospective controlled study conducted between March 1998 and January 2002 with a follow-up after six months. Setting: A non-invasive cardiac laboratory, medical department, Farwania Hospital. We studied 250 patients and divided them into two groups. The first group included 170 untreated hypertensive patients [140 men and 30 women] and the control group included 80 normotensive patients [70 men and 10 women]. Echocardiography was done to assess left ventricular mass index and function. Exercise ECG test was done for all patients at baseline. Hypertensive patients were classified into two subgroups. The first subgroup included 70 patients with normal heart rate recovery [> 12 beat/minute] and the second subgroup included 100 patients with impaired heart rate recovery [< 12 beat/minute]. A beta-blocker was prescribed for 50 patients and other antihypertensive drugs was prescribed for another 50 patients for six months. The exercise ECG test was repeated again for all 100 patients. T h e re was a significant impaired diastolic function of the left ventricle in hypertensive patients with impaired heart rate recovery than those with normal heart rate recovery [p < 0.05]. However there was no significant difference regarding left ventricular mass index and systolic function. There was a significant decrease in resting and peak heart rate during exercise in patients with beta-blockers than those without beta- blockers. There was a significant decline in heart rate after exercise in patients with beta-blockers at a follow-up check up [p < 0.05]. The decline in heart rate during the first minute of recovery after exercise at follow-up was more increased as compared with the results of baseline exercise ECG test [p < 0.01]. Stepwise logistic analysis revealed a significant relation between the age of the patients and left ventricular diastolic dysfunction and impaired heart rate recovery after exercise in hypertensive patients [p < 0.05]. Impaired heart rate recovery after exercise in hypertensive patients is related to the age of the patients and the presence of left ventricle diastolic dysfunction and that beta-blockers affect heart rate in recovery, most likely due to an indirect effect by the reduction of chronotropism