Background: The aim of this study is to evaluate heart rate recovery (HRR) and association between coronary flow rate and HRR in patients with metabolic syndrome (MS) who had morphologically normal coronary angiogram.
Methods: Study population included 43 patients with MS and 37 control subjects without MS. All patients were selected from individuals who had recently undergone coronary angiography in our hospital and were diagnosed as having angiographically normal coronary arteries. Exercise stress test results obtained prior to coronary angiography were evaluated for calculating HRR and other parameters. In addition, coronary flow was objectively evaluated for each major coronary artery in each subject using TIMI frame count method.
Results: All HRR values calculated were detected significantly lower in MS group compared to controls (HRR first: 32 ± 9 vs. 37 ± 10; p = 0.01, second: 46 ± 11 vs. 52 ± 11; p = 0.03, third: 51 ± 12 vs. 59 ± 12; p = 0.00, fourth: 54 ± 13 vs. 61 ± 2; p = 0.02). TIMI frame counts for each major epicardial coronary artery and mean TIMI frame count were also found to be significantly higher in MS group compared to controls (left anterior descending artery:51 ± 24 vs. 39 ± 15; p = 0.009, left circumflex artery: 32 ± 11 vs. 24 ± 7; p = 0.001, right coronary artery: 33 ± 14 vs. 24 ± 10; p = 0.003, mean TIMI frame count: 38 ± 15 vs. 29 ± 9;p = 0.002). Additionally, significant negative correlations were also detected between HRR first minute and coronary TIMI frame count values in patients with MS. None of MS parameters did not affect HRR values, however mean TIMI frame count independently associated with HRR first minute (p = 0.04) in patients with MS.
Conclusions: Impaired coronary blood flow occurring in MS might be a clue of autonomic dysfunction in addition to previously known endothelial dysfunction.