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Reduced heart rate response to dipyridamole in patients undergoing myocardial perfusion SPECT
Gozde Daglioz Gorur1, Esra Alkan Ciftci, Guliz Kozdag
1Department of Nuclear Medicine, Kocaeli University School of Medicine, Umuttepe, Kocaeli, 41380, Turkey. gozdedaglioz@yahoo.com
Insights
Reduced heart rate (HR) response to dipyridamole is common in myocardial perfusion SPECT imaging. Low high-density lipoprotein (HDL) levels and chronic renal failure predict this reduced HR response, linked to ventricular dysfunction.
Area of Science:
- Cardiology
- Nuclear Medicine
- Diagnostic Imaging
Background:
- Dipyridamole is used for myocardial perfusion imaging.
- A normal hemodynamic response includes increased heart rate (HR).
- Reduced HR response may indicate underlying pathology.
Purpose of the Study:
- Investigate HR response to dipyridamole during myocardial perfusion SPECT.
- Identify predictors of reduced HR response.
Main Methods:
- 201 patients undergoing dipyridamole stress Tc99m-MIBI or Tl-201 gated myocardial perfusion SPECT were enrolled.
- Reduced HR response defined as HR ratio (peak HR/rest HR) ≤ 1.20.
- Logistic regression analysis identified predictors of reduced HR response.
Main Results:
- 78% of patients exhibited reduced HR response.
- Predictors included diabetes mellitus, chronic renal failure, and low HDL.
- Reduced HR response was associated with lower ejection fractions and higher perfusion scores.
Conclusions:
- Reduced HR response to dipyridamole is linked to ventricular dysfunction and cardiac autonomic neuropathy.
- Low HDL levels are associated with reduced HR response.
- Chronic renal failure also predicts reduced HR response.
Objective:
A mild decrease in blood pressure and increase in heart rate (HR) are considered normal hemodynamic responses to dipyridamole. In this study, we tried to investigate HR response to dipyridamole and its predictors in patients undergoing gated myocardial perfusion single photon emission computed tomography (SPECT).
Methods:
201 consecutive patients undergoing dipyridamole stress Tc99m-MIBI or Tl-201 gated myocardial perfusion SPECT were prospectively enrolled. Dipyridamole was infused over 4 min and radiopharmaceutical was injected 3 min after the end of infusion. A reduced heart rate response to dipyridamole considered if the HR ratio (peak HR/rest HR) was 1.20 or less. Stress (sLVEF), rest (rLVEF) left ventricular ejection fractions, stress and rest motion (SMS, RMS) and thickening scores (STS, RTS) were derived automatically by QGS. Summed stress score (SSS), summed rest score (SRS), and summed difference score (SDS) for myocardial perfusion were calculated. Patients were grouped according to HR response and groups were compared. A logistic regression analysis was used to determine independent predictors of reduced HR response.
Results:
Reduced HR response was found in 78 % of patients. Patients with abnormal HR response were more frequently had a history of diabetes mellitus, chronic renal failure, and had lower high-density lipoprotein (HDL) levels. Peak HR, SSS, SRS, sLVEF and rLVEF were lower; rest HR, RTS, and the number of patients with ≤ 45 % sLVEF and rLVEF were higher in reduced HR response group (all p < 0.05). There was no difference between groups by means of gender, rest and peak systolic or diastolic tension, SDS, SMS, STS, RMS, history of hypertension, peripheral arterial disease, metabolic syndrome, coronary interventions, digoxin, calcium channel blocker or beta blocker usage. Multivariable logistic regression analysis demonstrated that the independent predictors of reduced HR response were HDL, rest HR and SSS. When HDL was removed from the model, chronic renal failure also emerged as an independent predictor.
Conclusion:
Reduced HR response to dipyridamole is associated with ventricular dysfunction, cardiac autonomic neuropathy. Low HDL levels also seem to be related with reduced HR response.
