Author's reply: To PMID 24818624.

To the Editor,

We would like to thank the authors for their comments on our original investigation published in the Anatolian Journal of Cardiology 20142014;14:351-6. (1). We defined abnormal heart rate recovery (HRR) as ≤21 beats during the first minute of recovery in a sitting position and found that abnormal HRR is sensitive with regard to the diagnosis of coronary artery disease (CAD) (76.1%) but does not exhibit good specificity (41.3%). We suggest that the presence of abnormal HRR (≤21 beats) in treadmill exercise testing should be considered an additional diagnostic criterion for the presence of CAD, and therefore, we agree that HRR should be incorporated into the interpretation of treadmill exercise testing (TET), in addition to other significant parameters, such as ST-segment depression, typical chest pain, or hypotensive response.

Normal parasympathetic reactivation is needed for the rapid decrease in heart rate following the cessation of exercise. Therefore, slow HRR after exercise has prognostic value for predicting cardiovascular mortality, regardless of the extent of coronary disease (2). However, several risk factors for atherosclerosis, especially metabolic syndrome components (3), advancing age (4), and chronic obstructive pulmonary disease (5), are important factors of decreased HRR. Because the risk factors mentioned above are also strongly associated with CAD, the calculation of HRR, as well as traditional markers of ischemic response during TET, could provide additional diagnostic information about the presence of CAD.