Efficacy of pre-scan beta-blockade and impact of heart rate on image quality in patients undergoing coronary multidetector computed tomography angiography

Subtraction coronary CT angiography in patients with high heart rate

All the previous subtraction coronary CT angiography (CCTA) had strict heart rate (HR) inclusion criteria. In this study, a new subtraction method was applied to patients with various HR. The post-contrast scan time was respectively 3.5 s after ascending aorta peak enhancement while HR >80 bpm, 4 s while 65≤ HR ≤80 bpm and 4.5 s while HR <65 bpm. Forty-six patients who underwent the new subtraction protocol were enrolled and patients were stratified into the high HR group (≥70 bpm) and low HR group (<70 bpm). Eighteen patients with 15 severe calcification segments and 25 stent segments further received invasive coronary angiography (ICA). In all included patients, the coronary artery enhancement was compared between the high and low HR groups. In patients with ICA performed, the image quality improvement and diagnostic effectiveness for detection of significant coronary segments stenosis (>50%) were compared between the conventional CCTA and subtraction CCTA and between the high HR group and low HR group, respectively. All enrolled patients got sufficient coronary artery enhancement. In patients with ICA performed, receiver operating characteristic (ROC) curve analysis showed that the area under the curve (AUC) for the diagnosis of significant stenosis was 0.93 in subtraction CCTA and 0.73 in conventional CCTA (p < 0.05). Furthermore, there were no significant differences in image quality improvement, specificity, positive predictive value and accuracy between the high HR group and low HR group. The new subtraction CCTA method broadened the clinical availability for patients with high HR.

Coronary CTA Amidst the COVID-19 Pandemic: A Quicker Examination Protocol with Preserved Image Quality Using a Dedicated Cardiac Scanner

There has been an ongoing debate on the means to minimize the time patients spend at health care providers during the COVID-19 pandemic. We propose a strategy relying solely on intravenous (i.v.) beta-blocker administration for heart-rate (HR) control prior to coronary CT angiography (CCTA). We aimed to assess a potential difference in CCTA image quality (IQ) after implementation of a modified strategy compared to our standard protocol of oral premedication during the first wave of COVID-19. We analyzed CCTA examinations conducted one year before (n = 1511) and after (n = 1064) implementation of this new regime. Examinations were performed both on our 256-slice multidetector CT (MDCT) and dedicated cardiac CT (DCCT) scanners. We used a four-point Likert scale (excellent/good/moderate/non-diagnostic) for IQ assessment of the coronaries. We detected a significant increase in mean HR during examinations on both CT scanners (MDCT: 62.4 ± 10.0 vs. 65.3 ± 9.7, p < 0.001; DCCT: 61.7 ± 15.2 vs. 65.0 ± 10.7, p < 0.001). The rate of moderate/non-diagnostic IQ significantly increased on the MDCT (192/1005, 19.1% vs. 144/466, 30.9%, p < 0.001), while this ratio did not change significantly on the DCCT (62/506, 12.3% vs. 84/598, 14.0%, p = 0.38). The improved temporal resolution of DCCT allows the stand-alone use of i.v. premedication with preserved IQ; hence, the duration of visits can be shortened.

Speeding up beta-blockade prior to coronary CT angiography: can we predict the dose of intravenous metoprolol required to achieve target heart rate in a given patient?

AIM

To evaluate the use and safety of intravenous (IV) metoprolol in a cohort of patients undergoing coronary computed tomographic angiography (CCTA) at a university hospital, and in particular, to establish if the minimum dose required to achieve the target heart rate (HR) in a given patient can be predicted from the baseline HR.

MATERIALS AND METHODS

Patients undergoing CCTA at a tertiary centre between January 2015 and May 2018, with baseline HR ≥60 bpm requiring IV metoprolol, were identified retrospectively from the database. Patients with a contraindication to beta-blockade or an indication for CCTA other than coronary disease were excluded. HR at baseline and at the time of scanning were recorded, together with the total dose of IV metoprolol administered.

RESULTS

Of 625 patients identified, 330 (52.8%) achieved HR ≤60 with IV metoprolol. Patients who achieved target HR had lower baseline HR. They received a lower radiation exposure due to tight prospective gating and a lower tube voltage. The lower quartile dose of metoprolol administered was 5 mg for patients with baseline HR <65 beats per minute (bpm), but 10 mg for HR 65-74 bpm, and ≥20 mg for higher HRs. There were no cases of symptomatic bradycardia/hypotension.

CONCLUSION

Patients with a resting HR of ≥60 bpm can reasonably be given an initial minimum dose of 5-20 mg metoprolol IV before CCTA, with additional doses as required.

Effectiveness of point-of-care oral ivabradine for cardiac computed tomography

BACKGROUND

Coronary CT angiography (CCTA) is increasing seen as a first line investigation in patients with suspected coronary artery disease. Heart-rate control improves the image quality and diagnostic accuracy of CCTA. Typically, beta-blockers are administered to induce sinus bradycardia. Sinus bradycardia may also be induced by ivabradine. We hypothesized that in a real-world population ivabradine would be an effective alternative to metoprolol at heart rate lowering for CCTA.

METHODS

This was a retrospective analysis of consecutive patients who were exposed to an ivabradine-based (IB) versus a metoprolol-only (MO) protocol to achieve a target heart rate </ = 65bpm. Hemodynamic responses to both strategies were compared along with differences in cost and the time expired from medication administration to CCTA.

RESULTS

5955 consecutive patients were included in the analysis: 3211 were imaged during an era of a metoprolol only strategy (MO) and 2744 CCTA following an ivabradine based (IB) strategy. 2676 patients had heart rates >65 and received heart-rate lowering medication: 1958 patients had MO, and 718 received IB protocol. Target heart rate of </ = 65bpm was achieved in 77% of MO and 89% of IB patients (p < 0.01). The time from initial medication administration to CCTA was longer in the IB versus MO patients (77 versus 48 min, p < 0.01).

CONCLUSIONS

Introduction of a novel single dose ivabradine-based protocol to control heart rate for CCTA was more successful in achieving target heart rate than a metoprolol-only strategy. The use of ivabradine however incurred a 1.6-fold increase in the time delay from medication administration and imaging compared to a metoprolol only protocol.

Practical instructions for using drugs in CT and MR cardiac imaging

The progressive increase in numbers of noninvasive cardiac imaging examinations broadens the spectrum of knowledge radiologists are expected to acquire in the management of drugs during CT coronary angiography (CTCA) and cardiac MR (CMR) to improve image quality for optimal visualization and assessment of the coronary arteries and adequate MR functional analysis. Aim of this review is to provide an overview on different class of drugs (nitrate, beta-blockers, ivabradine, anxiolytic, adenosine, dobutamine, atropine, dipyridamole and regadenoson) that can be used in CTCA and CMR, illustrating their main indications, contraindications, efficacy, mechanism of action, metabolism, safety, side effects or complications, and providing advices in their use.

Questionable necessity of nitroglycerin for diagnostic coronary artery examination using 320-row multi-detector computed tomography

OBJECTIVE

This study aims to analyze and compare the diagnostic effectiveness of 320-row multi-detector computed tomography for coronary artery angiography (MDCTA) in subjects with and without sublingual vasodilator (nitroglycerin).

MATERIALS AND METHODS

From September 2015 to September 2016, 70 individuals without history of major cardiovascular diseases who underwent MDCTA for health examination were retrospectively categorized into sublingual nitroglycerin (NTG) and non-NTG groups. Medical history, CT dose index (CTDI), and multi-slice CT images were compared between two groups. A diameter of coronary artery (DA, mm) was computed and analyzed.

RESULTS

A total of 41 males and 29 females (mean age: 55.43±8.84 years, range: 34- 76) were reviewed. Normal and abnormal MDCTA findings were noted in 54 and 16 participants, respectively, with the detection rate of coronary artery disease being 23%. There was no significant difference in inter-observer variability of coronary CTA image quality and diagnosis between the NTG and non-NTG groups among three experienced radiologists. Although the percentage dilatation of left anterior descending branch (LAD), right coronary artery (RCA) and left circumflex branch (LCX) following in the NTG group were 12.4%, 12.8% and 25.3%, respectively (p < 0.01), there was no significant difference in image quality and diagnosis between the two groups.

CONCLUSIONS

Despite the recommendation of routine nitroglycerin use for subjects undergoing computed tomography for coronary artery angiography, our results showed no significant advantage of its use in improving image quality and rate of diagnosis accuracy.

Image Quality, Overall Evaluability, and Effective Radiation Dose of Coronary Computed Tomography Angiography With Prospective Electrocardiographic Triggering Plus Intracycle Motion Correction Algorithm in Patients With a Heart Rate Over 65 Beats Per Minute

PURPOSE

Recently, a new intracycle motion correction algorithm (MCA) was introduced to reduce motion artifacts from heart rate (HR) in coronary computed tomography angiography (cCTA). The aim of the study was to evaluate the image quality, overall evaluability, and effective radiation dose (ED) of cCTA with prospective electrocardiographic (ECG) triggering plus MCA as compared with standard protocol with retrospective ECG triggering in patients with HR≥65 bpm.

MATERIALS AND METHODS

One hundred consecutive patients (67±10 y) scheduled for cCTA with 65<HR<80 bpm were retrospectively analyzed. The patients were assigned to 2 groups undergoing prospective (group 1) or retrospective (group 2) triggered cCTA. The study protocol was approved by the Institutional Ethics Committee and a written informed consent was obtained from all patients. Image noise, signal to noise ratio, contrast to noise ratio, Likert image quality score (score 1, nondiagnostic; score 2, adequate; score 3, good; score 4, excellent), overall image evaluability, and ED were measured and compared between the 2 groups. Both vessel-based and patient-based analyses were evaluated. Student test or Wilcoxon test were used to evaluate differences of continuous variables, whereas the χ test was used to study differences with regard to categorical data. A P-value <0.05 was considered statistically significant.

RESULTS

cCTA was successfully performed in all patients. In a segment-based model, group 1 compared with group 2 showed a lower rate of overall artifacts (67% vs. 83%; P<0.001) and motion artifacts (49% vs. 66%; P<0.001), resulting in a better Likert image quality score (2.83±1.03 vs. 2.37±1.02; P<0.01) and overall evaluability (85% vs. 75%; P<0.01). Group 1 showed a lower ED as compared with group 2 (3.1±1.9 vs. 11.9±3.3 mSv; P<0.01).

CONCLUSION

MCA and cCTA with prospective ECG-triggering acquisition in patients with high HR improves image quality and overall evaluability compared with cCTA with standard retrospective ECG triggering.

SEALONE (Safety and Efficacy of Coronary Computed Tomography Angiography with Low Dose in Patients Visiting Emergency Room) trial: study protocol for a randomized controlled trial

Objective

Chest pain is one of the most common complaints in the emergency department (ED). Cardiac computed tomography angiography (CCTA) is a frequently used tool for the early triage of patients with low- to intermediate-risk acute chest pain. We present a study protocol for a multicenter prospective randomized controlled clinical trial testing the hypothesis that a low-dose CCTA protocol using prospective electrocardiogram (ECG)-triggering and limited-scan range can provide sufficient diagnostic safety for early triage of patients with acute chest pain.

Methods

The trial will include 681 younger adult (aged 20 to 55) patients visiting EDs of three academic hospitals for acute chest pain or equivalent symptoms who require further evaluation to rule out acute coronary syndrome. Participants will be randomly allocated to either low-dose or conventional CCTA protocol at a 2:1 ratio. The low-dose group will undergo CCTA with prospective ECG-triggering and restricted scan range from sub-carina to heart base. The conventional protocol group will undergo CCTA with retrospective ECG-gating covering the entire chest. Patient disposition is determined based on computed tomography findings and clinical progression and all patients are followed for a month. The primary objective is to prove that the chance of experiencing any hard event within 30 days after a negative low-dose CCTA is less than 1%. The secondary objectives are comparisons of the amount of radiation exposure, ED length of stay and overall cost.

Results and Conclusion

Our low-dose protocol is readily applicable to current multi-detector computed tomography devices. If this study proves its safety and efficacy, dose-reduction without purchasing of expensive newer devices would be possible.

Reduction of Coronary Motion Artifacts in Prospectively Electrocardiography-Gated Coronary Computed Tomography Angiography Using Monochromatic Imaging at Various Energy Levels in Combination With a Motion Correction Algorithm on Single-Source Fast Tube Voltage Switching Dual-Energy Computed Tomography: A Phantom Experiment

OBJECTIVES

The aim of this study was to assess the effect of monochromatic imaging at various energy levels in combination with a motion correction algorithm (MCA) in single-source dual-energy coronary computed tomography angiography (CCTA) with fast switching of tube voltage on the reduction of coronary motion artifacts (CMA) in a phantom setting.

MATERIALS AND METHODS

Using this dual-energy computed tomography technique with a phantom comprising models of coronary vessels filled with contrast medium and pulsating at constant heart rates of 60 to 100 beats per minute, we reconstructed monochromatic images of CCTA obtained at 50 to 90 keV with and without use of MCA. Cardiac motion was modeled by simulating the in vivo time-volume curve of the left ventricle. Two independent readers graded CMA in 9 coronary segments using a 5-point scale (1, poor; 3 to 5, interpretable; 5, excellent). At each heart rate, we compared the average score of CMA between images obtained at 50 to 90 keV with and without use of MCA using Wilcoxon signed rank test, and we compared the score among images obtained at 50 to 90 keV with use of MCA using Kruskal-Wallis and post hoc tests. We also compared the percentages of image interpretability and improvement in image interpretability among images obtained at 50 to 90 keV with use of MCA.

RESULTS

With the use of MCA, the average score of CMA was significantly higher for images obtained at each energy level from 50 to 70 keV (P < 0.05) and was comparable at 80 and 90 keV, and it was comparable among those obtained at 50 to 70 keV. With its use, the percentages of image interpretability were similarly high at 50 to 70 keV at 60 to 80 beats per minute (78%-100%), and they were higher at 50 to 60 keV (72%-83%) than at 70 keV at 90 to 100 beats per minute (50%-56%). The percentages of improved image interpretability with MCA were similarly high at 50 to 70 keV at 60 to 80 beats per minute (56%-100%), and they were higher at 50 to 60 keV (62%-77%) than at 70 keV at 90 to 100 beats per minute (36%-43%). The percentages of image interpretability and improved image interpretability with MCA were insufficient at 80 and 90 keV.

CONCLUSIONS

Coronary motion artifacts were significantly reduced in images of monochromatic CCTA obtained at 50 to 70 keV in combination with MCA compared with those obtained without MCA, and the percentages of image interpretability and improved image interpretability with use of MCA were relatively high at 50 to 70 keV, and particularly at 50 to 60 keV, even at 90 to 100 beats per minute.

Computed tomography coronary angiography with heart rate control premedication: a best practice implementation project

BACKGROUND

Computed tomography coronary angiography patient preparation with heart rate control premedication is employed in departments across Australia. However, the methods of administration vary widely between institutions and do not always follow best practice.

OBJECTIVES

This aim of the study was to identify and promote best practice in the administration of heart rate premedication in computed tomography coronary angiography at a regional hospital in Australia.

METHODS

The Joanna Briggs Institute have validated audit and feedback tools to assist with best practice implementation projects. This project used these tools, which involve three phases of activity - a pre-implementation audit, reflecting on results and implementing strategies to address non-compliance, and a post-implementation audit to assess the outcomes.

RESULTS

A baseline audit identified non-compliance in the majority of measured audit criteria. Following implementation of an institution-specific guideline and associated worksheet, improved compliance was shown across all audit criteria.

CONCLUSIONS

Following the development and implementation of institution-specific evidence-based resources relating to heart rate control in computed tomography coronary angiography, a high level of compliance consistent with best practice was achieved.

Impact of heart rate on diagnostic accuracy of second generation 320-detector computed tomography coronary angiography

OBJECTIVE

To assess the impact of elevated heart rate (HR) on the diagnostic accuracy and image quality of second-generation 320-detector computed tomography coronary angiography (320-CTCA).

METHODS

Consecutive patients with suspected coronary disease referred for invasive coronary angiography (ICA) were prospectively recruited and underwent 320-CTCA. Pre-scan beta-blockers were administered if native HR>80 bpm and post-scan cohorts stratified by traditional (HR ≤60 bpm) and elevated HR (61-80 bpm). A wider phase window was used for the elevated HR group (30-80%). 320-CTCA and ICA were analyzed by independent readers blinded to other data. Significant disease was defined as ≥50% visual stenosis on ICA. Uninterpretable segments by 320-CTCA were considered to be significant on an intention-to-diagnose principle. Image quality was assessed by 5-point Likert score.

RESULTS

Of 107 patients studied (1,662 segments), there was no significant difference in sensitivity, specificity, positive and negative predictive value between patients with HR ≤60 bpm (n=55) vs. HR 61-80 bpm (n=52): 97%, 88%, 95%, 94% vs. 100%, 88%, 95%, 100%; Receiver operator characteristic-area under the curve 0.93 vs. 0.94, P=0.82). Overall per-patient diagnostic accuracy was 96% in both groups with no significant difference in interpretable segments (Likert ≥2) or median radiation dose (2.4 mSv vs. 2.7 mSv, P=0.35). Only 4/1,662 (0.2%) segments were uninterpretable by motion artefact in the whole cohort.

CONCLUSIONS

In patients with HR >60 and up to 80bpm, second generation 320-CTCA provides comparably adequate diagnostic accuracy to HR ≤60 without significantly impacting upon overall segmental evaluability.

Image quality in coronary CT angiography: challenges and technical solutions

Multidetector CT angiography (CTA) has become a widely accepted examination for non-invasive evaluation of the heart and coronary arteries. Despite its ongoing success and worldwide clinical implementation, it remains an often-challenging procedure in which image quality, and hence diagnostic value, is determined by both technical and patient-related factors. Thorough knowledge of these factors is important to obtain high-quality examinations. In this review, we discuss several key elements that may adversely affect coronary CTA image quality as well as potential measures that can be taken to mitigate their impact. In addition, several recent vendor-specific advances and future directions to improve image quality are discussed.

Bailout intravenous esmolol for heart rate control in cardiac computed tomography angiography

OBJECTIVE

To evaluate the efficacy and safety of a heart rate (HR) reduction protocol using intravenous esmolol as bailout for failed oral metoprolol regimens in patients undergoing coronary computed tomography angiography (CCTA) with 64-slice multidetector computed tomography (64-MDCT).

METHODS

Patients who underwent cardiac 64-MDCT in a single institution between 2011 and 2014 were analyzed. Those with HR above 60 beats per minute (bpm) on presentation received oral metoprolol (50-200 mg) at least one hour before CCTA. Intravenous esmolol 1-2 mg/kg was administered as a bolus whenever HR remained over 65 bpm just before imaging. The primary efficacy endpoint was HR <65 bpm during CCTA. The primary safety endpoint was symptomatic hypotension or bradycardia up to hospital discharge.

RESULTS

During the study period CCTA was performed in 947 cases. In 86% of these, oral metoprolol was the only medication required to successfully reduce HR <60 bpm. Esmolol was used in the remaining 130 patients (14%). For esmolol-treated patients mean baseline and acquisition HR were 74±14 bpm and 63±9 bpm, respectively (p<0.001). The target HR of <65 bpm was achieved in 82 of the 130 esmolol-treated patients (63%). Considering the whole population, esmolol use led to a significant increase in the primary efficacy endpoint from 86% to 95% (p<0.001). Esmolol also resulted in a statistically, but not clinically, significant reduction in systolic blood pressure (144±22 to 115±17 mmHg; p<0.001). The combined primary safety endpoint was only observed in two (1.5%) patients.

CONCLUSION

Despite optimal use of oral beta-blockers, 14% of patients needed intravenous esmolol for HR control. The pre-medication combination of oral metoprolol and on-demand administration of intravenous esmolol was safe and effective and enabled 95% of patients to be imaged with HR below 65 bpm.

Coronary Computed Tomography Angiography: Patient-related factors determining image quality using a second-generation 320-slice CT scanner

PURPOSE

To investigate the diagnostic confidence of Coronary Computed Tomography Angiography (CCTA) and the effect of patient-related factors on CCTA image quality using a second-generation 320-slice scanner.

METHODS AND RESULTS

200 consecutive patients (mean age 60±12years; 109 men) prospectively underwent CCTA. The mean body mass index (BMI) was 27.1±4.9kg/m(2); the median heart rate (HR) was 60.0 (interquartile range (IQR), 53.9-66.1) beats per minute (bpm). The median segment's diameter was 2.8 (IQR, 2.2-3.4) mm. For each coronary segment ≥1.5mm in diameter, two readers scored: diameter narrowing as < or ≥50%, overall diagnostic confidence and motion-related image quality, with interobserver agreement kappa-values of 0.89, 0.91 and 0.61 respectively. Seventy-nine of the 2505 evaluated segments (3.2%) had non-diagnostic image quality because of coronary calcifications (66/79; 83.5%), stent- (6/79; 7.5%), pacemaker- (2/79; 2.5%) or motion-related artifacts (5/79; 6.5%). The effect of patient-related factors on motion-related image quality was investigated by multinomial logistic regression in 181 patients with calcium score (IQR, 0-446.5). Increasing coronary diameter was the most improving image quality factor (odds ratio (OR), 1.8637; p<0.001), marginally followed by lower HR (OR, 0.9547; p<0.001) and calcium score (OR, 0.9997; p=0.04). Gender (p=0.70), age (p=0.24) and BMI (p=0.45) did not affect image quality.

CONCLUSION

Using a second-generation 320-slice scanner, CCTA diagnostic confidence is predominantly affected by coronary calcifications, whereas motion-related image quality is non-diagnostic only in exceptional cases and mainly influenced by the coronary diameter. For future developments, our study findings therefore suggest greater requirements concerning spatial resolution and calcium-related artifact removal than concerning temporal resolution, especially to improve diagnostic confidence in patient groups with smaller coronary diameters.

Impact of an intra-cycle motion correction algorithm on overall evaluability and diagnostic accuracy of computed tomography coronary angiography

OBJECTIVES

The aim of this study was to evaluate the impact of a novel intra-cycle motion correction algorithm (MCA) on overall evaluability and diagnostic accuracy of cardiac computed tomography coronary angiography (CCT).

METHODS

From a cohort of 900 consecutive patients referred for CCT for suspected coronary artery disease (CAD), we enrolled 160 (18 %) patients (mean age 65.3 ± 11.7 years, 101 male) with at least one coronary segment classified as non-evaluable for motion artefacts. The CCT data sets were evaluated using a standard reconstruction algorithm (SRA) and MCA and compared in terms of subjective image quality, evaluability and diagnostic accuracy.

RESULTS

The mean heart rate during the examination was 68.3 ± 9.4 bpm. The MCA showed a higher Likert score (3.1 ± 0.9 vs. 2.5 ± 1.1, p < 0.001) and evaluability (94%vs.79 %, p < 0.001) than the SRA. In a 45-patient subgroup studied by clinically indicated invasive coronary angiography, specificity, positive predictive value and accuracy were higher in MCA vs. SRA in segment-based and vessel-based models, respectively (87%vs.73 %, 50%vs.34 %, 85%vs.73 %, p < 0.001 and 62%vs.28 %, 66%vs.51 % and 75%vs.57 %, p < 0.001). In a patient-based model, MCA showed higher accuracy vs. SCA (93%vs.76 %, p < 0.05).

CONCLUSIONS

MCA can significantly improve subjective image quality, overall evaluability and diagnostic accuracy of CCT.

KEY POINTS

Cardiac computed tomographic coronary angiography (CCT) allows non-invasive evaluation of coronary arteries. Intra-cycle motion correction algorithm (MCA) allows for compensation of coronary motion. An MCA improves image quality, CCT evaluability and diagnostic accuracy.

Impact of beta-blockade premedication on image quality of ECG-gated thoracic aorta CT angiography

BACKGROUND

Thoracic aortic aneurysm is one of the most common aorta pathologies worldwide, which is commonly evaluated by computed tomography angiography (CTA). One of the routine methods to improve the image quality of CTA is heart rate reduction prior to study by beta-blockade administration.

PURPOSE

To assess the effect of beta-blockade on image quality of the ascending aorta in electrocardiography (ECG)-gated dual-source CTA (DSCTA) images.

MATERIAL AND METHODS

In this retrospective study, ECG-gated thoracic aorta CTA images of 40 patients without beta-blocker administration were compared with ECG-gated images of 40 patients with beta-blockade. Images of the aorta were analyzed objectively and subjectively at three levels: sinus of Valsalva (sinus), sinotubular junction (STJ), and mid ascending aorta (MAA). Quantitative sharpness index (SI) and signal-to-noise ratio (SNR) were calculated and two radiologists evaluated the image quality using a 3-point scale.

RESULTS

Mean heart rate in beta-blocker and non-beta-blocker groups was 61.7 beats per minute (bpm) (range, 58.1-63.9 bpm) and 72.9 bpm (range, 69.3-84.1 bpm), respectively (P < 0.05). Aorta wall SI, SNR, and subjective grading were comparable between the two groups at all three levels (P > 0.05).

CONCLUSION

Beta-blocker premedication may not be necessary for imaging of ascending aorta with ECG-gated DSCTA.

A comparison of bolus injection of landiolol versus oral administration of propranolol before cardiac computed tomography

Heart rate (HR) reduction is essential to achieve good image quality for cardiac computed tomography (CCT). We evaluated the efficacy of a bolus injection of landiolol, an ultra-short acting β-blocker, without the administration of oral β-blocker to reduce HR prior to CCT. We enrolled 678 consecutive patients who underwent CCT from December 2011 to March 2012 and divided them into three groups, which were a propranolol group (n = 277), a low-dose landiolol group (n = 188), and a high-dose landiolol group (n = 213). Patients in the propranolol group received oral propranolol (10–20 mg) prior to CCT. Patients in the low-dose and high-dose landiolol groups were administered a bolus injection of landiolol (0.125 mg/kg), while the high-dose group received an additional 3.75 mg of landiolol if the baseline HR was ≥75/min. Although the average HR was significantly lower in the propranolol group (61.6 ± 8.0/min) than in the low-dose landiolol group (64.1 ± 7.4/min, P < 0.001), there was no significant difference in the image quality (P = 0.91). Among patients with baseline HR ≥75/min, the average HR tended to be lower in the high-dose landiolol group (67.2 ± 6.9/min) compared with the low-dose landiolol group (69.0 ± 6.9/min, P = 0.10), and there was a corresponding difference in image quality between these two groups (P = 0.02). In conclusion, Although the decrease of HR was significantly larger in the propranolol group than in the landiolol groups, the image quality was similar. Among the patients who received landiolol, a higher dose was associated with a lower HR and better image quality. Further investigation to assess higher-dose bolus injection of landiolol or bolus injection following oral administration of a β-blocker would be needed.

Heart rate control with single administration of a long-acting β-blocker at bedtime before coronary computed tomography angiography

BACKGROUND

Beta-blockers are used to control the heart rate prior to coronary computed tomography (CT) angiography. However, in-hospital administration is time-consuming, and it is hard to decrease the heart rate to <60 beats per minute (bpm) when the initial heart rate is increased. In this study, we examined whether the single administration of long-acting β-blocker at bedtime before angiography is effective for achieving the target heart rate.

METHODS AND RESULTS

A total of 314 consecutive patients with a resting heart rate >60bpm who underwent coronary CT angiography were retrospectively collected. Either bisoprolol or atenolol was orally administered the night before to 166 patients (beta group), and no additional medication was administered to the other 148 patients (control group). When the heart rate was >60bpm on arrival, a β-blocker or verapamil was orally administered at the discretion of the physician. Although the baseline heart rate was not significantly different between the groups, the β-blocker treatment the night before significantly reduced the heart rate compared to control group upon arrival at the hospital and at the time of angiography. The rate of achievement of a heart rate ≤60bpm on arrival at the hospital was significantly higher in the beta group, and even after the additional treatment.

CONCLUSIONS

Bedtime administration of a long-acting β-blocker the night before coronary CT angiography is an effective option to achieve the target heart rate at the time of examination.

Absorbed radiation dose in radiosensitive organs using 64- and 320-row multidetector computed tomography: a comparative study

Aim. To determine absorbed radiation dose (ARD) in radiosensitive organs during prospective and full phase dose modulation using ECG-gated MDCTA scanner under 64- and 320-row detector modes. Methods. Female phantom was used to measure organ radiation dose. Five DP-3 radiation detectors were used to measure ARD to lungs, breast, and thyroid using the Aquilion ONE scanner in 64- and 320-row modes using both prospective and dose modulation in full phase acquisition. Five measurements were made using three tube voltages: 100, 120, and 135 kVp at 400 mA at heart rate (HR) of 60 and 75 bpm for each protocol. Mean acquisition was recorded in milligrays (mGy). Results. Mean ARD was less for 320-row versus 64-row mode for each imaging protocol. Prospective EKG-gated imaging protocol resulted in a statistically lower ARD using 320-row versus 64-row modes for midbreast (6.728 versus 19.687 mGy, P < 0.001), lung (6.102 versus 21.841 mGy, P < 0.001), and thyroid gland (0.208 versus 0.913 mGy; P < 0.001). Retrospective imaging using 320- versus 64-row modes showed lower ARD for midbreast (10.839 versus 43.169 mGy, P < 0.001), lung (8.848 versus 47.877 mGy, P < 0.001), and thyroid gland (0.057 versus 2.091 mGy; P < 0.001). ARD reduction was observed at lower kVp and heart rate. Conclusions. Dose reduction to radiosensitive organs is achieved using 320-row compared to 64-row modes for both prospective and retrospective gating, whereas 64-row mode is equivalent to the same model 64-row MDCT scanner.

Single dose ivabradine versus intravenous metoprolol for heart rate reduction before coronary computed tomography angiography (CCTA) in patients receiving long-term calcium channel-blocker therapy

BACKGROUND

In patients with contraindication for beta-blockers who are also under long-term calcium channel-blocker therapy for any reason, ivabradine may be used as an alternative treatment to achieve the target heart rate.

PURPOSE

To assess whether single dose oral ivabradine in patients referred for coronary computed tomography angiography (CCTA) is safe and can significantly decrease heart rate compared to intravenous (i.v.) metoprolol in patients receiving long-term calcium channel-blocker therapy.

MATERIAL AND METHODS

One-hundred and twenty patients who were under calcium channel-blocker therapy referred for CCTA were randomized to premedication with single dose (15 mg) ivabradine (n = 63) or i.v. metoprolol (5-10 mg) (n = 62). Hearth rate (HR) was assessed at admission (HR1), prescan (HR2), and during CCTA scan (HR3) for all patients. Blood pressure (BP) was measured before medication (BP1) and immediately before CCTA scan (BP2).

RESULTS

Although the HR averages of two groups were not significantly different before medication (HRIv1 = 80 ± 7 bpm vs. HRβ1 = 81 ± 7 bpm; P = 0.42), significant HR reduction was observed in the ivabradine group (HRIv3 = 62 ± 7 bpm) when compared to the metoprolol group (HRβ3 = 66 ± 6 bpm; P = 0.001). Decreases in HR forivabradine (18 ± 6 bpm) was significantly higher than for metoprolol (15 ± 4 bpm; P = 0.003) without relevant side-effects. Ivabradine showed no significant effect on either systolic BP or diastolic BP (siBPIv1, 139 ± 10; siBPIv2, 138 ± 10; P = 0.260; diBPIv1, 81 ± 7; diBPIv2, 81 ± 6; P = 0.59). Nevertheless, metoprolol group demonstrated significant reduction in both SiBP and DiBP (siBPβ1, 136 ± 11; siBPβ2 130 ± 11; P < 0.001; diBPβ1, 81 ± 6; diBPβ2, 78 ± 6; P < 0.001).

CONCLUSION

Single dose ivabradine is safe and significantly more effective than i.v. metoprolol in decreasing HR in patients under calcium channel-blocker therapy.

Cost minimization analysis of beta-blocker at the time of CT imaging for suspected of coronary heart disease in Japan

OBJECTIVES

To conduct a cost-minimization analysis of landiolol for CT diagnosis of coronary heart diseases in patients with tachycardia in Japan.

METHODS

A decision-tree model was constructed to analyze costs from the healthcare payer's perspective. Drug costs and diagnosis costs, computer tomography coronary angiography (CTCA), and coronary angiography (CAG), are adopted to the model. Landiolol is administered only to slow the heart rate to take CT images appropriately. Since some trials proved that there was no difference between landiolol and placebo in terms of efficacy and safety, this study conducted cost-minimization analysis. Of those suspected of coronary heart diseases, 22.5% are thought to be taking beta-blockers. The success rates for CT scanning for landiolol and placebo, derived from domestic trial data, were 81.4% (96/118, 77.8-84.9%) and 54.2% (64/118, 49.7-58.8%). Patients who failed to take a CT image were thought to take CAG. The healthcare cost was derived from a Japanese fee schedule. Costs of landiolol, CT imaging, and CAG are JPY2634 (USD1 = JPY100, as of November 20, 2013), JPY38,116, and JPY101,322, respectively. The positive rate for CAG, derived from domestic trial data, was 37.1% (33/89, 32.0-42.2%). Various sensitivity analyses, both univariate and probabilistic ones, were conducted.

RESULTS

In the base case analysis, expected costs per patient for landiolol and placebo were JPY78,956 and JPY82,232, respectively. In budget impact analysis, 81,062 patients are eligible for landiolol and it can save JPY266million for whole patients. Sensitivity analyses suggested the robustness of the results.

LIMITATIONS

This study did not consider any adverse effects in the decision-tree model. This model was developed especially for measuring the cost-saving effect of landiolol, through decreasing the number of patients who require CAG, due to imaging failure.

CONCLUSIONS

Landiolol for CTCA diagnosis in patients suspected of coronary heart disease with tachycardia is thought to be cost saving.

Impact of β(1)- and β(2)-adrenergic receptor gene single nucleotide polymorphisms on heart rate response to metoprolol prior to coronary computed tomographic angiography

A slow, steady heart rate (HR) is necessary for optimal image quality during coronary computed tomographic angiography. Beta blockers are often used, but the goal HR is not achieved in some patients. The aim of this study was to examine the influence of single-nucleotide polymorphisms (SNPs) of the β(1) (codons 49 and 389) and β(2) (codons 16, 27, and 164) adrenergic receptor (AR) genes on HR response to metoprolol in 200 adults (mean age 56 ± 11 years) referred for coronary computed tomographic angiography (using a 64-slice scanner). Oral and intravenous (IV) metoprolol was given to achieve a goal HR of <60 beats/min. Overall, 37 patients (18.5%) did not reach the goal HR despite the administration of oral (181 ± 116 mg) and IV (4.2 ± 9.4 mg) metoprolol. Patients with the β(1)-AR Ser49Gly or Gly49Gly genotype (n = 49) more often failed to reach an optimal HR compared to those with the Ser49Ser genotype (n = 151) (29% vs 15%, p = 0.04), despite receiving higher doses of oral (210 ± 115 vs 172 ± 115 mg, p = 0.048) and IV (7 ± 13 vs 3 ± 8 mg, p = 0.02) metoprolol. Similarly, patients with the β(1)-AR Gly389Gly genotype (n = 11) more often failed to reach an optimal HR compared to those with the Arg389Arg and Arg389Gly genotypes (n = 189) (45% vs 17%, p = 0.02), despite receiving higher doses of IV (13 ± 15 vs 4 ± 9 mg, p = 0.002) but not oral (162 ± 105 vs 182 ± 117 mg, p = 0.50) metoprolol. Multivariate analysis identified β(1)-AR SNPs at codons 49 and 389 and β(2)-AR SNP at codon 27 as independent predictors of suboptimal HR response. In conclusion, these data indicate that the selected SNPs of β(1)-AR and β(2)-AR genes influence HR response to metoprolol in patients who undergo coronary computed tomographic angiography.

Safety and efficacy of oral ivabradine as a heart rate-reducing agent in patients undergoing CT coronary angiography

OBJECTIVE

To investigate the role of oral ivabradine as a heart rate reducing agent in patients undergoing CT coronary angiography (CTCA). Despite the routine use of β-blockers prior to CTCA studies, it is not uncommon to have patients with heart rates persistently above the target range of 65 bpm. Ivabradine is a selective inhibitor of the I(f) current, which primarily contributes to sinus node pacemaker activity, and has no significant direct cardiovascular effects such as reduction of blood pressure, cardiac contractility or impairment of cardiac conduction.

METHODS

We investigated 100 consecutive patients who had been referred for CTCA for the evaluation of suspected coronary artery disease (CAD). Patients were randomised to receive either of the following two pre-medication protocols: oral metorprolol or oral ivabradine.

RESULTS

Ivabradine was significantly more effective than metorprolol in lowering the heart rate; the mean percentage reduction in heart rate with ivabradine vs metorpolol was 23.89+6.95% vs 15.20+4.50%, respectively (p=0.0001). Metoprolol significantly lowered both systolic and diastolic blood pressure while ivabradine did not. The requirement of additional doses to achieve a target heart rate of <65 beats per min was also significantly more frequent with metoprolol.

CONCLUSION

Ivabradine is a potentially attractive alternative to currently used drugs for reduction of heart rate in patients undergoing CTCA.

Nonrigid registration-based coronary artery motion correction for cardiac computed tomography

PURPOSE

X-ray computed tomography angiography (CTA) is the modality of choice to noninvasively monitor and diagnose heart disease with coronary artery health and stenosis detection being of particular interest. Reliable, clinically relevant coronary artery imaging mandates high spatiotemporal resolution. However, advances in intrinsic scanner spatial resolution (CT scanners are available which combine nearly 900 detector columns with focal spot oversampling) can be tempered by motion blurring, particularly in patients with unstable heartbeats. As a result, recently numerous methods have been devised to improve coronary CTA imaging. Solutions involving hardware, multisector algorithms, or β-blockers are limited by cost, oversimplifying assumptions about cardiac motion, and populations showing contraindications to drugs, respectively. This work introduces an inexpensive algorithmic solution that retrospectively improves the temporal resolution of coronary CTA without significantly affecting spatial resolution.

METHODS

Given the goal of ruling out coronary stenosis, the method focuses on "deblurring" the coronary arteries. The approach makes no assumptions about cardiac motion, can be used on exams acquired at high heart rates (even over 75 beats/min), and draws on a fast and accurate three-dimensional (3D) nonrigid bidirectional labeled point matching approach to estimate the trajectories of the coronary arteries during image acquisition. Motion compensation is achieved by employing a 3D warping of a series of partial reconstructions based on the estimated motion fields. Each of these partial reconstructions is created from data acquired over a short time interval. For brevity, the algorithm "Subphasic Warp and Add" (SWA) reconstruction.

RESULTS

The performance of the new motion estimation-compensation approach was evaluated by a systematic observer study conducted using nine human cardiac CTA exams acquired over a range of average heart rates between 68 and 86 beats/min. Algorithm performance was based-lined against exams reconstructed using standard filtered-backprojection (FBP). The study was performed by three experienced reviewers using the American Heart Association's 15-segment model. All vessel segments were evaluated to quantify their viability to allow a clinical diagnosis before and after motion estimation-compensation using SWA. To the best of the authors' knowledge this is the first such observer study to show that an image processing-based software approach can improve the clinical diagnostic value of CTA for coronary artery evaluation.

CONCLUSIONS

Results from the observer study show that the SWA method described here can dramatically reduce coronary artery motion and preserve real pathology, without affecting spatial resolution. In particular, the method successfully mitigated motion artifacts in 75% of all initially nondiagnostic coronary artery segments, and in over 45% of the cases this improvement was enough to make a previously nondiagnostic vessel segment clinically diagnostic.

Ivabradine versus metoprolol for heart rate reduction before coronary computed tomography angiography

Several studies have demonstrated the correlation of heart rate (HR) and image quality in coronary computed tomography angiography. Beta-blocker administration is critical because of its negative inotropic effect. Ivabradine is a selective HR-lowering agent that exclusively inhibits the I(f) current in sinoatrial node cells without having any effect on cardiac contractility or atrioventricular conduction. A total of 120 patients were randomized to oral premedication with ivabradine 15 mg or metoprolol 50 mg. HR and blood pressure (BP) were measured before the administration of premedication and immediately before coronary computed tomographic angiography. The mean time between premedication administration and follow-up was 108 ± 21.5 minutes for ivabradine and 110 ± 22.2 minutes for metoprolol (p = NS). When comparing groups, there were no significant differences in reduction of HR (-11.83 ± 8.6 vs -13.20 ± 7.8 beats/min, p = NS) and diastolic BP (-5.05 ± 14.2 mm Hg vs -4.08 ± 10.8 mm Hg, p = NS), whereas the decrease of systolic BP was significantly lower in patients who received ivabradine compared to those in the metoprolol group (-3.95 ± 13.6 vs -13.65 ± 17.3 mm Hg, p <0.001). In the subgroup of patients who were receiving long-term β-blocker therapy, significantly stronger HR reduction was achieved with ivabradine (-13.19 ± 5.4 vs -10.04 ± 6.0 beats/min, p <0.05), while the decrease in systolic BP was less (-2.00 ± 13.6 vs -15.04 ± 20.8 mm Hg, p <0.05) compared to metoprolol. In conclusion, ivabradine decreases HR before coronary computed tomographic angiography sufficiently, with significantly less depression of systolic BP compared to metoprolol.

"In-house" pharmacological management for computed tomography coronary angiography: heart rate reduction, timing and safety of different drugs used during patient preparation

We retrospectively evaluated the effect, timing and safety of different pharmacological strategies during 64-slice CT coronary angiography (CT-CA). From the institutional database of CT-CAwe enrolled 560 consecutive patients with suspected coronary artery disease. The type of drug preparation (group 1 = no treatment; group 2 = oral metoprolol; group 3 = other; group 4 = intravenous (IV) atenolol; group 5 = IV atenolol + nitrates; NR = non-responders), timing, and adverse effects were recorded. Heart rate (HR) during different preparation phases was recorded. Four adverse effects were recorded, none of which was attributable to pharmacological treatment. In all groups, except group 1, the HR on arrival was significantly reduced by the pharmacological treatment (p<0.01). Group 4 showed the best (-16±8 bpm) HR reduction. There was no significant effect on HR due to nitrates (p = 0.49), while a slight increase due to contrast material was noted (p<0.05). Average time required for preparation was 44±25min. Groups 4 and 5 showed the most effective timing (8±9 min and 8±8 min, respectively; p<0.01). Pharmacological preparation in patients undergoing CT-CA is safe and effective. Best results in terms of HR reduction and fast preparation are obtained with IV administration of beta-blockers.

Comparison of a low-osmolar contrast medium, iopamidol, and an iso-osmolar contrast medium, iodixanol, in MDCT coronary angiography

OBJECTIVE

To prospectively compare iopamidol 370, which is a low-osmolar contrast medium and iodixanol 320, which is an iso-osmolar contrast medium, in terms of image quality and nonserious adverse effects that have the potential to influence the image quality in a 16-slice multi-detector row computed tomography coronary angiography.

METHODS

Sixty patients were divided into two groups to receive iodixanol 320 or iopamidol 370. Image quality was assessed, using a five-point grading scale. Differences in the mean attenuation (Hounsfield units) at the origin of the coronary arteries and on the ascending aorta in both the groups were compared. The number and intensity of adverse effects were compared between the two groups.

RESULTS

The mean attenuation values of the ascending aorta and the origins of the coronary arteries for the two groups showed no significant difference (P≥0.41). There was no significant difference in terms of image quality between the two groups on all evaluated segments. There was a statistically significant difference in the number of adverse effects (P=0.001) between the two groups. However, in both the iodixanol group and the iopamidol group, there was no significant difference in terms of image quality between the patients with and without adverse effects.

CONCLUSION

The frequency of adverse effects is lower in the iodixanol group than the iopamidol group. Iodixanol 320 can provide both vascular enhancement and image quality, which is similar to iopamidol 370 in a 16-slice multi-detector row computed tomography coronary angiography. There was no significant difference in terms of overall image quality between the patients with and without adverse effects in either of the groups.

Absorbed radiation dose in radiosensitive organs during coronary CT angiography using 320-MDCT: effect of maximum tube voltage and heart rate variations

OBJECTIVE

The purpose of this article is to estimate the absorbed radiation dose in radiosensitive organs during coronary MDCT angiography using 320-MDCT and to determine the effects of tube voltage variation and heart rate (HR) control on absorbed radiation dose.

MATERIALS AND METHODS

Semiconductor field effect transistor detectors were used to measure absorbed radiation doses for the thyroid, midbreast, breast, and midlung in an anthropomorphic phantom at 100, 120, and 135 kVp at two different HRs of 60 and 75 beats per minute (bpm) with a scan field of view of 320 mm, 400 mA, 320 × 0.5 mm detectors, and 160 mm collimator width (160 mm range). The paired Student's t test was used for data evaluation.

RESULTS

At 60 bpm, absorbed radiation doses for 100, 120, and 135 kVp were 13.41 ± 3.59, 21.7 ± 4.12, and 29.28 ± 5.17 mGy, respectively, for midbreast; 11.76 ± 0.58, 18.86 ± 1.06, and 24.82 ± 1.45 mGy, respectively, for breast; 12.19 ± 2.59, 19.09 ± 3.12, and 26.48 ± 5.0 mGy, respectively, for lung; and 0.37 ± 0.14, 0.69 ± 0.14, and 0.92 ± 0.2 mGy, respectively, for thyroid. Corresponding absorbed radiation doses for 75 bpm were 38.34 ± 2.02, 59.72 ± 3.13, and 77.8 ± 3.67 mGy for midbreast; 26.2 ± 1.74, 44 ± 1.11, and 52.84 ± 4.07 mGy for breast; 38.02 ± 1.58, 58.89 ± 1.68, and 78 ± 2.93 mGy for lung; and 0.79 ± 0.233, 1.04 ± 0.18, and 2.24 ± 0.52 mGy for thyroid. Absorbed radiation dose changes were significant for all organs for both tube voltage reductions as well as for HR control from 75 to 60 bpm at all tube voltage settings (p < 0.05). The absorbed radiation doses for the calcium score protocol were 11.2 ± 1.4 mGy for midbreast, 9.12 ± 0.48 mGy for breast, 10.36 ± 1.3 mGy for lung, and 0.4 ± 0.05 mGy for thyroid.

CONCLUSION

CT angiography with 320-MDCT scanners results in absorbed radiation doses in radiosensitive organs that compare favorably to those previously reported. Significant dose reductions can be achieved by tube voltage reductions and HR control.

Safety, efficacy, and indications of beta-adrenergic receptor blockade to reduce heart rate prior to coronary CT angiography

For selected indications, coronary computed tomographic (CT) angiography is an established clinical technology for evaluation in patients suspected of having or known to have coronary artery disease. In coronary CT angiography, image quality is highly dependent on heart rate, with heart rate reduction to less than 60 beats per minute being important for both image quality and radiation dose reduction, especially when single-source CT scanners are used. β-Blockers are the first-line option for short-term reduction of heart rate prior to coronary CT angiography. In recent years, multiple β-blocker administration protocols with oral and/or intravenous application have been proposed. This review article provides an overview of the indications, efficacy, and safety of β-blockade protocols prior to coronary CT angiography with respect to different scanner techniques. Moreover, implications for radiation exposure and left ventricular function analysis are discussed.

Current techniques for MR imaging of atherosclerosis

Vessel wall imaging of large vessels has the potential to identify culprit atherosclerotic plaques that lead to cardiovascular events. Comprehensive assessment of atherosclerotic plaque size, composition, and biological activity is possible with magnetic resonance imaging (MRI). Magnetic resonance imaging of the atherosclerotic plaque has demonstrated high accuracy and measurement reproducibility for plaque size. The accuracy of in vivo multicontrast MRI for identification of plaque composition has been validated against histological findings. Magnetic resonance imaging markers of plaque biological activity such as neovasculature and inflammation have been demonstrated. In contrast to other plaque imaging modalities, MRI can be used to study multiple vascular beds noninvasively over time. In this review, we compare the status of in vivo plaque imaging by MRI to competing imaging modalities. Recent MR technological improvements allow fast, accurate, and reproducible plaque imaging. An overview of current MRI techniques required for carotid plaque imaging including hardware, specialized pulse sequences, and processing algorithms are presented. In addition, the application of these techniques to coronary, aortic, and peripheral vascular beds is reviewed.

Safety and efficacy of a drug regimen to control heart rate during 64-slice ECG-gated coronary CTA in children

BACKGROUND

The adult practice for ECG-gated single-source 64-slice coronary CTA (CCTA) includes administering beta-blockers to reduce heart rate. There are limited data on this process in children.

OBJECTIVE

To evaluate the safety and efficacy of a drug regimen to decrease heart rate before performing CCTA in children.

MATERIALS & METHODS

IV remifentanil and esmolol infusion were chosen to decrease heart rate in 41 children (mean age 6.5 years) while they were under general anesthesia (GA) for CCTA. Drug doses, changes in heart rate and procedural complications were recorded. CCTA image quality was graded on a scale of 1 to 5. The relationships between image quality and heart rate and image quality and age were evaluated. Patient effective radiation doses were calculated.

RESULTS

Heart rates were lowered utilizing esmolol (4 children), remifentanil (2 children) or both (35 children); 26 children received nitroglycerin for coronary vasodilation. The mean decrease in heart rate was 26%. There were no major complications. The average image-quality score was 4.4. Higher heart rates were associated with worse image quality (r = 0.67, P < 0.0001). Older age was associated with better image quality (r = 0.66, P < 0.0001). Effective radiation doses were 0.7 to 7.0 mSv.

CONCLUSION

Heart rate reduction for pediatric CCTA can be safely and effectively achieved while yielding high-quality images.

Incremental value and safety of oral ivabradine for heart rate reduction in computed tomography coronary angiography

BACKGROUND

Heart rate (HR) reduction is essential to achieve optimal image quality and diagnostic accuracy with computed tomography coronary angiography (CTCA). Administration of ivabradine could be an attractive alternative to beta-blockade to reduce HR.

METHODS

One-hundred-twenty-three patients referred for CTCA were prospectively enrolled. Patients were divided in two groups depending on the absence or presence of chronic beta-blockade treatment. Within the two groups patients were randomized to either no additional premedication or oral ivabradine for 5 days prior to CTCA. In presence of chronic beta-blockade therapy it was shifted to atenolol 50mg twice a day for 5 days prior to CTCA. HR and blood pressure were assessed at admission (T0), immediately before CTCA (T1) and during CTCA (T2). The target HR was <65 bpm.

RESULTS

Ivabradine significantly reduced HR during CTCA. Mean relative HR reduction was 15% for controls, 12% for chronic beta-blockade, 19% for ivabradine and 24% for both chronic beta-blockade and ivabradine at T2 (p for trend <0.001). The rate of patients who reached the target HR at T2 was 83% in controls, 71% with chronic beta-blockade, 97% with ivabradine and 97% with both (p for trend <0.05). The percentage of patients that needed additional IV beta-blockade at T1 decreased from 69% to 40% with ivabradine and 30% with both (p for trend <0.05).

CONCLUSIONS

Ivabradine is safe and effective in increasing the rate of patients at target HR and in reducing the need for additional IV beta-blockade in patients referred for CTCA.

Strategies for radiation-dose reduction and image-quality optimization in multidetector computed tomographic coronary angiography

The technological evolution of computed tomography (CT) in the last decade has placed CT coronary angiography (CTCA) in the spotlight of imaging modalities available to evaluate patients with coronary artery disease. Widespread utilisation of CTCA has generated concern from the medical community regarding potential health issues related to the significant radiation exposure associated with this method, and several modifications of the CTCA technique have been proposed to reduce the radiation exposure without affecting the diagnostic image quality. This review will discuss a practical approach to performing CTCA to ensure that the radiation dose is minimized while maintaining diagnostic image quality.