Target heart rate to determine the normal value of coronary flow reserve during dobutamine stress echocardiography

Abstract

BackgroundThe determination of coronary flow reserve (CFR) is an essential concept at the moment of decision-making in ischemic heart disease. There are several direct and indirect tests to evaluate this parameter. In this sense, dobutamine stress echocardiography is one of the pharmacological method most commonly used worldwide. It has been previously demonstrated that CFR can be determined by this technique. Despite our wide experience with dobutamine stress echocardiography, we ignored the necessary heart rate to consider sufficient the test for the analysis of CFR. For this reason, our main goal was to determine the velocity of coronary flow in each stage of dobutamine stress echocardiography and the heart rate value necessary to double the baseline values of coronary flow velocity in the territory of the left anterior descending (LAD) coronary artery.MethodsA total of 33 consecutive patients were analyzed. The patients included had low risk for coronary artery disease. All the participants underwent dobutamine stress echocardiography and coronary artery flow velocity was evaluated in the distal segment of LAD coronary artery using transthoracic color-Doppler echocardiography.ResultsThe feasibility of determining CFR in the territory of the LAD during dobutamine stress echocardiography was high: 31/33 patients (94%). Mean CFR was 2.67 at de end of dobutamine test.There was an excellent concordance between delta HR (difference between baseline HR and maximum HR) and the increase in the CFR (correlation coefficient 0.84). In this sense, we found that when HR increased by 50 beats, CFR was ≥ 2 (CI 93-99.2%). In addition, 96.4% of patients reached a CFR ≥ 2 (IC 91.1 - 99%) at 75% of their predicted maximum heart rate.ConclusionsWe found that the feasibility of dobutamine stress echocardiography to determine CFR in the territory of the LAD coronary artery was high. In this study, it was necessary to achieve a difference of 50 bpm from baseline HR or at least 75% of the maximum predicted heart rate to consider sufficient the test for the analysis of CFR.

Coronary Flow Velocity Reserve during Pharmacologic Stress Echocardiography with Normal Contractility Adds Important Prognostic Value in Diabetic and Nondiabetic Patients

“…7 At present, the possibility of determining mean distal flow in the LAD and its CFVR exceeds 95% of patients evaluated. 21,24,25 The CFVR information is additive to the exclusive wall motion result, as confirmed in a meta-analysis performed of five studies by Rigo, 10 which included our experience, 11 showing an increase in diagnostic sensitivity (from 67 6 9% to 90 6 3%) with scarce loss of specificity (from 93 6 2% to 86 6 12%) and remarkable increase in test accuracy (from 79 6 5% to 89 6 7%). Yet the prognostic value of CFVR has been explored in depth only in recent years.…”

“…21 In the present study, 53.9% of patients were assessed under dobutamine (351 of 651), with a feasibility of 90%, slightly lower than that with dipyridamole. The results showed that dobutamine was as efficient as dipyridamole to predict events, without significant differences between the two stress agents (Figure 4).…”

“…CFVR was defined as the ratio between maximum diastolic flow velocity at peak stress and baseline flow velocity, considering as abnormal a value <2. 7,20,21 It was categorized in 4 groups according to its absolute value: >2, 1.99 to 1.75, 1.74 to 1.5, and <1.49.…”

Assessment of Coronary Flow During Stress Testing: Does it Add Diagnostic and Prognostic Value?

“…13. It is extremely important to reach a delta heart rate of at least 50 bpm or a heart rate of at least 75% of the maximum predicted heart rate to consider a CFR value abnormal [36].…”

Sphingosine-1-Phosphate Receptor Agonist, FTY720, Restores Coronary Flow Reserve in Diabetic Rats

“…Some studies reported that heart rate and blood pressure can impact CFR. 43 Further research is required to investigate whether FTY720 has an impact on the heart rate of diabetic rats.…”