Point-of-care screening for left ventricular hypertrophy and concentric geometry using hand-held cardiac ultrasound in hypertensive patients.

BACKGROUND: The introduction of the hand-held cardiac ultrasound (HCU) may potentially increase detection of LV hypertrophy in hypertensive patients. However, whether point-of-care screening for LV hypertrophy and concentric LV geometry by HCU in hypertensive patients is feasible and comparable to that of standard state-of-the-art echocardiography (SE) evaluation remains to be elucidated. METHODS AND RESULTS: Accordingly, one hundred consecutive patients (66 female, mean age=58±13 years, 32% African-American, mean body mass index=31±8 kg/m(2)) with the diagnosis of hypertension underwent both HCU and SE examinations in tandem. A cardiology fellow-in-training performed the HCU exam while a cardiac sonographer performed the SE. 37% of hypertensive patients had electrocardiographic LV hypertrophy by Sokolow-Lyon or Cornell voltage criteria. Mean LV mass was 210±42 g with the HCU and 209±40 g with SE. Mean relative wall thickness was 0.45±0.05 by the HCUD and 0.44±0.05 by SE. There was excellent correlation between LV mass and relative wall thickness measurements by HCU and SE (r=0.985, SEE=6.8 g and r=0.762, SEE=0.33, respectively, both p<0.001). The prevalence of LV hypertrophy using prognostically-validated partition values for LV mass/height(2.7) of 46.7 and 49.2 g/m(2.7) in women and men, respectively was 76% by HCU and 78% by SE (p=NS), with excellent agreement (92%, κ=0.774, p<0.001). Agreement for detection of concentric LV geometry (relative wall thickness>0.43) was also excellent (88%, κ =0.756, p<0.001). Agreement for LV hypertrophy and concentric geometry detection between the cardiology fellow-in-training and sonographer was excellent (κ =0.786, p<0.001). CONCLUSION: Point-of-care screening for LV hypertrophy and concentric LV geometry by HCU is feasible and correlates very well with that of SE. HCU may allow for immediate point-of-care assessment and treatment of cardiac target organ damage in hypertensive patients.

Does cardiac SPECT using attenuation and scatter correction accurately predict coronary artery disease in a minority women population?

BACKGROUND: Myocardial perfusion imaging (MPI) is a well-established diagnostic method for evaluation and risk stratification of coronary artery disease (CAD). We undertook this study to validate both the positive predictive value (when compared to cardiac catheterization) and the prognosis afforded by MPI in a group of minority women patients. MATERIAL/METHODS: The database of our Nuclear Imaging and Catheterization Laboratory was retrospectively queried for consecutive minority (African-American, Hispanic and Asian) women patients who underwent MPI and cardiac catheterization within 90 days of each other. Patients with recent revascularization were excluded. Attenuation/scatter correction was utilized in the final interpretation of the study. RESULTS: Of the 54 women patients who underwent MPI, 7 underwent exercise stress testing, 26 had stress testing with adenosine, 18 with dipyridamole and 3 with dobutamine. Eighteen patients (53%) had same number of vessels predicted by MPI and coronary angiography (7 patients with triple vessel disease, 7 with 2-vessel disease and 4 with single vessel disease). Five (3 with intermediate and 2 with high risk scans) out of the 54 patients (9.3%) were dead at 2 years. The sensitivity, specificity and positive predictive value of MPI as compared to angiography were 87.2%, 26.7%, 75.6% and 44.4% respectively. CONCLUSIONS: The sensitivity of MPI in this group of patients is comparable to the general population though the specificity is lower in spite of using attenuation and scatter correction. Low risk perfusion scan signifies favorable prognosis at 2 years with regards to mortality.

Are transthoracic echocardiographic parameters associated with atrial fibrillation recurrence or stroke? Results from the Atrial Fibrillation Follow-Up Investigation of Rhythm Management (AFFIRM) study.

OBJECTIVES: The purpose of this study was to evaluate the associations of transthoracic echocardiographic parameters with recurrent atrial fibrillation (AF) and/or stroke. BACKGROUND: The Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) study, an evaluation of elderly patients with AF at risk for stroke, provided an opportunity to evaluate the implications of echocardiographic parameters in patients with AF. METHODS: Transthoracic echocardiographic measures of mitral regurgitation (MR), left atrial (LA) diameter, and left ventricular (LV) function were evaluated in the AFFIRM rate- and rhythm-control patients who had sinus rhythm resume and had these data available. Risk for recurrent AF or stroke was evaluated with respect to transthoracic echocardiographic measures. RESULTS: Of 2,474 patients studied, 457 had > or =2(+)/4(+) MR, and 726 had a LA diameter >4.5 cm. The LV ejection fraction was abnormal in 543 patients. The cumulative probabilities of at least one AF recurrence/stroke were 46%/1% after 1 year and 84%/5% by the end of the trial (> 5 years), respectively. Multivariate analysis showed that randomization to the rhythm-control arm (hazard ratio [HR] = 0.64; p < 0.0001) and a qualifying episode of AF being the first known episode (HR = 0.70; p < 0.0001) were associated with decreased risk. Duration of qualifying AF episode >48 h (HR = 1.55; p < 0.0001) and LA diameter (p = 0.008) were associated with an increased risk of recurrent AF. Recurrent AF was more likely with larger LA diameters (HR = 1.21, 1.16, and 1.32 for mild, moderate, and severe enlargement, respectively). No transthoracic echocardiographic measures were associated with risk of stroke. CONCLUSIONS: In the AFFIRM study, large transthoracic echocardiographic LA diameters were associated with recurrent AF, but no measured echocardiographic parameter was associated with stroke.

Does scatter correction of cardiac SPECT improve image quality in the presence of high extracardiac activity?

BACKGROUND: Extracardiac activity confounds conventional cardiac single photon emission computed tomography (SPECT) image reconstruction. It has been proposed that applying scatter correction (SC) may improve image quality. This study was done to test whether SC improves several quantitative measures of cardiac imaging in the presence of high extracardiac activity. METHODS AND RESULTS: An anatomic anthropomorphic phantom with a cardiac insert filled with technetium 99m was used. We obtained acquisitions using a dual-headed SPECT camera at 13 different levels of liver-to-heart activity. Each acquisition was reconstructed by use of each of 6 different methods: filtered backprojection with or without SC, maximum likelihood with or without SC, and maximum likelihood with attenuation correction (AC) and with or without SC. Three different parameters were used to assess the effect of the processing methods on image quality: image variability, contrast, and signal-to-noise ratio. Only image contrast improved significantly with SC. By adding SC to filtered backprojection, image contrast improved by 13% (P <.01). Maximum likelihood reconstruction with AC resulted in further improvement in contrast (increase of 17%), variability (decrease of 5%), and signal-to-noise ratio (increase of 6%) over filtered backprojection (all P <.01). CONCLUSION: Image quality improved significantly when SC was applied, especially when combined with maximum likelihood reconstruction with AC. This improvement was present despite increased extracardiac activity in close proximity to the heart.

Do electrocardiographic changes with adenosine myocardial perfusion imaging predict ischaemia in patients with left ventricular hypertrophy?

BACKGROUND: Electrocardiographic (ECG) changes during adenosine myocardial perfusion imaging (MPI) correlate with severe coronary artery disease and the presence of collaterals. However, the significance of these changes during adenosine MPI in patients with left ventricular hypertrophy (LVH) on baseline electrocardiogram is less well understood. OBJECTIVE: To evaluate whether ECG changes on adenosine MPI predict ischaemia in patients with LVH. METHODS: We reviewed retrospectively 454 consecutive patients who had undergone adenosine MPI at our institution. The baseline electrocardiogram was reviewed to determine whether or not LVH was present. All patients were administered adenosine at 140 microg x kg x min for a total of 6 min and Tc-sestamibi was injected at 3 min into the protocol. None of the patients underwent any form of exercise during the stress test. RESULTS: Of the 146 patients with LVH, 10 had stress ECG changes suggestive of ischaemia and 40 had evidence of ischaemia on MPI. Similarly, of the 308 patients without LVH, 43 had stress ECG changes suggestive of ischaemia and 68 had ischaemia on MPI. The sensitivity and specificity of stress ECG changes in predicting ischaemia on perfusion in patients with LVH were 12.5% and 95.3%, respectively, with a positive predictive value of 50% and a negative predictive value of 74.3%. CONCLUSION: ECG changes suggestive of ischaemia in patients with LVH are very specific for ischaemia on MPI, and their significance is similar to that in patients without LVH.

Simple techniques to reduce bowel activity in cardiac SPECT imaging.

BACKGROUND AND AIM: Scatter from the bowel degrades image quality in 99mTc sestamibi myocardial perfusion imaging (MPI). Iodinated oral contrast, which has been used to outline bowel in medical imaging, absorbs X-rays as well as gamma rays. The purpose of this study was to test our hypothesis that iodinated oral contrast during MPI would absorb gamma rays emitted from 99mTc sestamibi in the bowel, thereby reducing scatter and improving cardiac SPECT images. METHODS AND RESULTS: Thirty subjects undergoing adenosine stress 99mTc sestamibi cardiac SPECT were randomized to receive either iodinated oral contrast (IOC), water or no intervention (controls). Subjects had 1 day rest-stress MPI using the adenosine stress protocol. Images were analysed using infra-cardiac counts, image variability, image contrast and the ratios of anterior to inferior and septal to lateral walls. The improvement in image contrast and variability between first and second images were significant in both the IOC and water groups. The IOC group had a more significant improvement in variability than did the water group. The reduction in infra-cardiac counts was also more significant in the IOC group. CONCLUSION: The use of oral contrast and water improved the image variability and contrast by decreasing the infra-cardiac scatter. The improvement was even more significant in the oral contrast group.

Assessment of left ventricular mass and geometry by cardiac single photon emission computed tomography.

BACKGROUND: Left ventricular (LV) hypertrophy is an independent predictor of increased morbidity and mortality. However, whether assessment of LV mass and geometry by cardiac single photon emission computed tomography (SPECT) is feasible remains unclear. MATERIAL/METHODS: We compared LV mass and geometry measured by cardiac SPECT to standard echocardiography in thirty consecutive patients (female 73%n mean age 22.64+/-17 years) who had both cardiac SPECT and echocardiography done less than 1 week apart. RESULTS: There was good correlation between the LV mass (r=0.73, p <0.001) and relative wall thickness (r=0.50, p<0.01) derived by cardiac SPECT to those of standard echocardiography. Using Bland-Altman method, the 95% confident interval of agreement between cardiac SPECT and standard echocardiography ranged from -52 g (5th percentile) to 124 g (95th percentile, mean difference =36+/-45) for LV mass and from -1 (5th percentile) to -0.6 (95th percentile, mean difference =-0.8+/-0.1) for relative wall thickness. CONCLUSIONS: Assessment of left ventricular mass and geometry using cardiac SPECT is feasible and may provide prognostic information beyond measurement of perfusion and function.

Correlation of myocardial p-(123)I-iodophenylpentadecanoic acid retention with (18)F-FDG accumulation during experimental low-flow ischemia.

UNLABELLED: Myocardial ischemia is associated with reduced free fatty acid (FFA) beta-oxidation and increased glucose utilization. This study evaluated the potential of dynamic SPECT imaging of a FFA analog, p-(123)I-iodophenylpentadecanoic acid (IPPA), for detection of ischemia and compares retention of IPPA with (18)F-FDG accumulation. METHODS: In a canine model of regional low-flow ischemia (n = 9), serial IPPA SPECT images (2 min per image) were acquired over 52--90 min. In a subset of dogs (n = 6), (18)F-FDG was injected after completing SPECT imaging and allowed to accumulate for 40 min before killing the animals. Flow was assessed with radiolabeled microspheres. Myocardial metabolism was evaluated independently by selective coronary arterial and venous sampling. RESULTS: Serial IPPA SPECT images showed an initial defect in the ischemic region (0.70% plus minus 0.03% ischemic-to-nonischemic ratio), which normalized within 48 min because of the slower IPPA clearance from the ischemic region (t(1/2) = 54.2 plus minus 3.3 min) relative to the nonischemic region (t(1/2) = 36.7 plus minus 5.6 min) (P < 0.05). Delayed myocardial IPPA and (18)F-FDG activities were correlated (r = 0.70; n = 576 segments), and both were maximally increased in segments with a moderate flow reduction (IPPA, 151% of nonischemic; (18)F-FDG, 450% of nonischemic; P < 0.05). CONCLUSION: Serial SPECT imaging showed delayed myocardial clearance of IPPA in ischemic regions with moderate flow reduction, which lead to increased late myocardial retention of IPPA. Retention of IPPA correlated with (18)F-FDG accumulation, supporting the potential of IPPA as a noninvasive marker of ischemic myocardium.

Renal artery stenosis: a cardiovascular perspective.

BACKGROUND: Renal artery stenosis (RAS) is an important clinical entity that can lead to uncontrolled hypertension and progressive renal failure. The most common causes of RAS are atherosclerosis and fibromuscular dysplasia. Because the diagnosis of renovascular hypertension is established only when revascularization of a stenosed renal artery results in cure or improvement in patients hypertension, establishment of a causal relationship between RAS and hypertension continues to present a challenge. Therefore, a high index of suspicion is essential in the diagnosis of this condition. METHODS: Multiple tests, both invasive and noninvasive, are available as screening methods. Angiography remains the gold standard for diagnosis of RAS. Besides its value in establishing the diagnosis, it provides anatomic information regarding the site and severity of stenoses and appropriate revascularization strategies. Magnetic resonance angiography and duplex ultrasonography are the most promising and accurate noninvasive screening tests available, even in the presence of renal insufficiency. With advances in percutaneous transluminal angioplasty techniques, including renal artery stenting, many more patients are eligible for less invasive and effective revascularization strategies compared with the traditional surgical procedures. RESULTS: Revascularization of a stenosed renal artery is associated with preservation of renal function and better control of hypertension, unstable angina, and congestive heart failure. Because atherosclerotic RAS is associated with generalized atherosclerosis, aggressive risk factor modification and antiplatelet therapy are integral in the management of RAS regardless of the revascularization strategy.

Association of heart rate response with scan and left ventricular function on adenosine myocardial perfusion imaging.

To evaluate the association of heart rate (HR) response with abnormal scan and/or left ventricular (LV) function in patients undergoing adenosine myocardial perfusion imaging, we retrospectively studied 188 consecutive patients who underwent a standard adenosine stress test (without exercise) and myocardial perfusion imaging (MPI) using technetium-99m sestamibi radioisotope. Change in HR was calculated by subtracting HR at rest from peak HR. The percentage change in HR was calculated. All patients underwent stress and resting single-photon emission computed tomography (SPECT) imaging. LV ejection fraction (EF) was calculated using gated SPECT. Mean age was 60 +/- 12 years and 135 of the patients (72%) were women. We divided the patients into 2 groups: group 1 (142 patients, 75%) had normal scans and group 2 (46 patients, 25%) had abnormal scans; abnormal scans were defined as presence of either fixed defects, reversible defects, or both. Average HR increased by 29 beats/min in the normal scan group compared with 19 beats/min in the abnormal scan group (p = 0.0004). Forty-seven patients (25%) had reduced EF (<45%). This group had an average HR and percentage HR increase of 20 beats/min (29%) compared with an increase of 29 beats/min (44%) in patients with normal EF (p = 0.002 and p = 0.002, respectively). Thus, a diminished HR response had a significant association with both an abnormal scan and reduced EF on adenosine MPI.