Ihab S. Ramzy

Electromechanical left ventricular behavior after nonsurgical septal reduction in patients with hypertrophic obstructive cardiomyopathy

OBJECTIVES To investigate the electromechanical consequences of nonsurgical septal reduction in a group of patients with hypertrophic obstructive cardiomyopathy (HOCM). BACKGROUND Patients with HOCM may benefit symptomatically from nonsurgical septal reduction as an alternative to dual chamber pacing and sensing (DDD) pacing and surgical myectomy. METHODS We studied 20 symptomatic patients with HOCM (12 men), mean age 52 +/- 17 years, before and after septal reduction using echocardiography and electrocardiogram (ECG). RESULTS Septal reduction with a significant rise in cardiac enzymes was successfully achieved in all patients resulting in a 50% reduction in resting left ventricular (LV) outflow tract gradient within 24 h of procedure and an 80% reduction after six months. Left ventricular outflow tract diameter increased at 24 h with a further increase six months later. QRS duration increased by 35 ms at 24 h after procedure associated with right bundle branch block (RBBB) and significant rightward axis rotation in 16 patients. R-wave amplitude in V1 fell by 7 +/- 4 mm in 15/20 patients, 13 of whom developed reduction of septal long axis excursion. Left-axis deviation appeared in three patients and septal q-wave was suppressed in 12 long-axis excursion; peak shortening and lengthening rates all fell at the septal site by 20% at 24 h. Only septal excursion returned back to baseline values at six months. Wall motion also became incoordinate so that postejection septal shortening increased by three times control values at 24 h and by four times six months later. CONCLUSIONS Nonsurgical septal reduction is associated with a drop in LV outflow tract obstruction and the creation of a localized myocardial infarction (MI) increasing LV outflow tract diameter. The technique also results in a consistent alteration of septal activation and secondary incoordination. The latter could play a significant role in gradient reduction and symptomatic improvement in a manner similar to that seen with DDD pacing.

Safety of contrast in stress echocardiography in stable patients and in patients with suspected acute coronary syndrome but negative 12-hour troponin.

Limited studies are available demonstrating the safety of contrast agents in patients undergoing stress echocardiography and none in patients with suspected acute coronary syndrome (ACS). Therefore, we sought to assess the safety profile of contrast agents in patients with stable chest pain and in those with suspected ACS (nondiagnostic electrocardiogram and negative initial 12-hour cardiac troponin test results). During a 4-year period, 3,704 patients underwent stress echocardiography (exercise or dobutamine), of whom, 929 (25%) had suspected ACS. Contrast agents (SonoVue 46%, Luminity 54%) were used in 1,150 patients (31%). No patients died with or without contrast administration. No nonfatal acute myocardial infarction occurred in patients administered contrast agents compared with 3 cases of acute myocardial infarction in the noncontrast group (p = 0.24). Two cases of sustained ventricular tachycardia developed, one in each group (p = 0.98). Compared with those who did not receive contrast, patients in both the stable chest pain and the suspected ACS groups had a greater burden of cardiovascular risk factors. The left ventricular function at rest was significantly worse in the patients who received contrast than in those who did not in the suspected ACS group. Also, a greater ischemic burden was present in those receiving contrast than in those not receiving it in both the stable chest pain and the suspected ACS groups. In conclusion, despite the presence of greater risk features compared with patients undergoing unenhanced stress echocardiography, the administration of ultrasound contrast agents (SonoVue and Luminity) in those with stable chest pain and those with suspected ACS was not associated with excess adverse events.

Right ventricular stunning in inferior myocardial infarction

AIM To assess right ventricular (RV) function in patients with inferior myocardial infarction (IMI) and to observe changes following thrombolysis. BACKGROUND RV dysfunction occurs in 30% of patients with IMI. The extent of such involvement and its potential, recovery has not been determined. METHODS We studied 30 patients with acute IMI (age 56+/-12 years), on admission, day 7 and day 30 post thrombolysis. No patient had clinical signs of RV failure. RV segmental function was assessed from free wall long axis and global function from filling and ejection velocities. Values were compared with 15 age-matched controls. RESULTS On admission, RV long axis amplitude, systolic and diastolic velocities were depressed (2.09+/-0.39 vs 2.6+/-0.3 cm, 8.18+/-1.8 vs 10.0+/-2.0 cm/s and 6.9+/-2.7 vs 10.0+/-2.5 cm/s, p<0.01 for all) and global function impaired; reduced Z ratio (0.85+/-0.07 vs 0.9+/-0.04, p<0.01), raised Tei index (0.49+/-0.26 vs 0.3+/-0.1, p<0.001) and prolonged t-IVT (8.16+/-3.9 vs 4.8+/-2 s/m, p<0.01) compared to controls. After thrombolysis, RV long axis amplitude (2.28+/-0.3 cm, p<0.05), systolic velocity (10.0+/-2.7 cm/s, p<0.01), early diastolic velocity (8.3+/-2.16, p<0.05), Z ratio (0.9+/-0.05, p<0.01), Tei index (0.34+/-0.17, p<0.01) and t-IVT (6.2+/-2.7 s/m, p<0.05) all normalised at day 30. Only 4 (13%) patients remained with RV long axis amplitude and one with t-IVT and Tei index values outside the normal 95% CI at day 30. RV inflow diameter and tricuspid regurgitation did not change. CONCLUSION In IMI, RV segmental and global functions are acutely impaired, and recover in 87% of patients following thrombolysis. In the absence of clear evidence for RV infarction the disturbances in the remaining 13% may represent stunned myocardium that may demonstrate delayed recovery.

The clinical impact of contemporary stress echocardiography in morbid obesity for the assessment of coronary artery disease

Objective Non-invasive cardiac imaging may suffer from poor image quality in morbidly obese individuals. This study aimed to determine the clinical value of contemporary stress echocardiography (SE) in morbidly obese patients referred for assessment of suspected coronary artery disease (CAD). Methods This prospective, multicentre observational study was conducted in two district hospitals and one tertiary centre in London, UK. Individuals with body mass index ≥35 kg/m2 referred for SE were evaluated. The percentage of patients with obstructive CAD on coronary angiography, following abnormal SE, was assessed. Patient outcomes were determined with follow-up for the composite end-point of all-cause mortality, myocardial infarction and late revascularisation. Results Over a 13-month period, 209 morbidly obese patients underwent SE, and contrast agent was used in 96% of patients. A diagnostic result was obtained in 200/209 (96%) patients. Of 32 (15%) patients with inducible ischaemia, 25 underwent angiography, 22 (88%) had corresponding significant CAD and, of these, 16 (77%) underwent revascularisation. Conversely, only 2/157 patients (1.3%) with normal SE underwent angiography, and none underwent revascularisation. Over a mean follow-up period of 17.8±5.4 months, there were nine events. The annualised cardiac event rate after a normal SE was 0.95%. Events were more frequent in patients with inducible ischaemia versus those without ischaemia (5/32 (15.6%) vs 4/153 (2.6%); p=0.002). Ejection fraction <50% (HR 9.5; 95% CI 2.4 to 38.0; p=0.002) and inducible ischaemia (HR 9.4; 95% CI 2.5 to 35.8; p=0.001) were predictors of outcome on univariable Cox regression analysis. Conclusions Contemporary SE has excellent feasibility and positive predictive value and resulted in appropriate risk stratification of symptomatic patients with significant obesity. A normal SE portends an excellent outcome over the short–intermediate term in this high-risk patient population.

The effect of the localization of Q wave myocardial infarction on ventricular electromechanics.

BACKGROUND The exact location of a Q wave myocardial infarction has an important effect on overall left ventricular function. OBJECTIVES To assess the effect of localization of Q wave infarction on left ventricular minor and long axis function, with particular reference to electromechanical disturbances. METHODS We studied 72 patients with Q wave myocardial infarction; 35 anterior, age 61+/-15 years and 37 inferior, age 62+/-12 years. ECG intervals were automatically measured by Hewlett-Packard Pagewriter and LV dimension and filling velocities studied by transthoracic echocardiography and simultaneous phonocardiogram. Findings were compared with 21 controls of similar age. RESULTS Heart rate and all ECG intervals were similar in the two patient groups and controls. QRS axis was more to the left in patients with inferior MI. Normal septal q wave was absent in lead V5 and V6 in 33/35 (94%) patients with anterior MI and in only 3/37 (8%) with inferior MI, p<0.001. LV minor axis dimensions were enlarged vs. normal (p<0.001) in the two patient groups and to a greater extent in anterior MI compared with inferior MI, p<0.05. Isovolumic relaxation time was prolonged only in-patients with an inferior MI, p<0.01. Long axis amplitude was globally reduced (p<0.001) in the two patient groups as were shortening and lengthening velocities (p<0.001). The onset of septal long axis shortening with respect to the q wave was delayed by 30 and 40 ms in inferior MI and anterior MI and that of lengthening with respect to A2 by 20 and 30 ms, respectively, compared to normal (p<0.001 for both). Post ejection shortening was localized to the septal long axis in 32/35 patients with anterior MI but was generalized involving all three LV long axes in inferior MI, p<0.001. Transmitral Doppler flow velocities and the frequency of mild mitral regurgitation were similar in the two groups. CONCLUSION These results confirm a close association between anterior Q wave infarction, septal incoordination and absent septal q waves. The global incoordinate long axis behaviour in inferior Q wave MI may be due to significant papillary muscle dysfunction, and results in significant shape change in early diastole. This disturbance in electromechanical behaviour might play an important role in the differing outcomes between the two different sites of myocardial infarction.

Electromechanical left atrial disturbances in acute inferior myocardial infarction : an evidence for ischaemic dysfunction

Electromechanical left atrial disturbances in acute inferior myocardial infarction : an evidence for ischaemic dysfunction

Electrocardiographic associations of right precordial Q waves help to distinguish anterior myocardial infarction from aortic stenosis

Right precordial Q waves are ECG evidence of anterior myocardial infarction and can be present in patients with pathological left ventricular hypertrophy particularly caused by aortic stenosis. The aim of this study was to investigate the ECG features associated with Q waves in aortic stenosis and those in anterior myocardial infarction. We studied 16 patients with anterior myocardial infarction and 19 patients with aortic stenosis by means of ECG, echocardiography and clinical history. On the ECG, heart rate (70 +/- 20 beats/min vs. 83 +/- 20) and QT interval (380 +/- 65 ms vs. 390 +/- 50) did not differ between the two conditions. PR interval (160 +/- 15 ms vs. 185 +/- 30, P<0.05) and QRS duration (80 +/- 7.0 ms vs. 95 +/- 15, P<0.01) were both longer in patients with aortic stenosis than in those with myocardial infarction. The Q wave voltage in V1 (1.0 +/- 0.55 mV vs. 1.5 +/- 0.60) or V2 (1.3 +/- 0.5 mV vs. 1.8 +/- 0.85) and R wave voltage in V5 (0.7 +/- 0.7 mV vs. 2.1 +/- 0.9) or V6 (0.7 +/- 0.4 mV vs. 1.5 +/- 0.7, all P<0.01) were significantly less in patients with anterior myocardial infarction than in those with aortic stenosis. Q wave voltage over 1.3 mV in V1 or R wave voltage over 1.5 mV in V5 can differentiate aortic stenosis from anterior myocardial infarction with a sensitivity of 79% for each and specificities of 81 and 93.8%, respectively. Though the frontal QRS axis was similar in the two groups (28 +/- 45 degrees vs. 14 +/- 35, P>0.05), the horizontal QRS axis pointed laterally (-30 +/- 20 degrees) in aortic stenosis and posteriorly (-60 +/- 20 degrees, P<0.01) in anterior myocardial infarction. A horizontal QRS axis between zero and -45 degrees detected the presence of aortic stenosis with a sensitivity of 94.7% and a specificity of 81.3%. On echocardiography, left ventricular hypertrophy was found in most patients (94.7%) with aortic stenosis but not in those (0%) with anterior myocardial infarction. Left ventricular end diastolic dimensions (5.1 +/- 0.7 cm vs. 5.1 +/- 0.9, P>0.05) were similar in the two groups but the end systolic dimension was increased in patients with aortic stenosis (4.0 +/- 0.9 cm vs. 3.4 +/- 0.6, P<0.05). The systolic left ventricular function (shortening fraction: 23 +/- 8.0% vs. 34 +/- 7.0; Vcf: 0.8 +/- 0.26 circ/s vs. 1.3 +/- 0.26, both P<0.01) was significantly impaired in patients with aortic stenosis compared to those with myocardial infarction. In conclusion, in the presence of right precordial Q waves, the simple 12-lead ECG can provide important information on distinguishing anterior myocardial infarction from aortic stenosis. In particular, the QRS voltage in the chest leads and horizontal QRS axis can differentiate anterior myocardial infarction from aortic stenosis with high sensitivity and specificity.

Exercise echocardiography in asymptomatic severe aortic stenosis

A 77 year old female with asymptomatic severe aortic stenosis (AS) and normal LV systolic function was referred for exercise stress echocardiography (ESE) in order to assess whether she is truly asymptomatic and to risk-stratify her aortic valve disease. While she only developed minimal breathlessness after 4.2 min of Bruce protocol and no other high risk features (arrhythmias, SBP drop, mean Aortic gradient rise [20 mmHg) [1], it was noted that her stroke volume (SV/ indexed SVi) and flow rate (FR) at peak stress had dropped compared to the ones at rest (SVi rest = 45.7 ml/m, SVi stress = 27 ml/m, FR rest = 234 ml/s, FR stress = 203 ml/ s). SV can drop physiologically during exercise due to reduction in ejection time [2]. However the drop in FR remained unexplained. This could be due to stress-induced myocardial dysfunction originating from global ischaemia due to AS or from myocardial ischaemia due to associated significant coronary artery disease (CAD). The patient had contrast ESE in order to assess for exercise induced LV dysfunction. This showed significant Regional Wall Thickening Abnormality in the left anterior descending (LAD) territory involving 9 out of 17 segments. She therefore underwent a coronary angiogram which confirmed features of tight proximal LAD disease (Fig. 1). Patient was referred for aortic valve replacement (AVR) and coronary artery bypass grafting. The above case highlights two important points. First that careful assessment of FR during ESE is crucial as FR reflects cardiac output. Secondly that the risk stratification of patients with asymptomatic severe AS using ESE should include assessment of regional wall thickening which may help to clarify the cause of exercise induced LV systolic dysfunction. The latter could be the result of ischaemia due to CAD and is a bad prognostic marker in severe AS.

115 Diagnostic concordance and clinical outcomes in patients undergoing fractional flow reserve and stress echocardiography for the assessment of coronary stenosis of intermediate severity

Introduction The ischaemic consequences of a coronary artery stenosis can be assessed by invasive fractional flow reserve (FFR) or by non-invasive imaging. We sought to determine (i) the concordance between wall thickening assessment and FFR during clinically indicated stress echocardiography (SE) and FFR measurements and (ii) the predictors of hard events in these patients. Methods and Results 194 patients who underwent SE and invasive FFR measurements in close succession were analysed for diagnostic concordance and clinical outcomes. At the vessel level, the sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of SE for identifying significant disease as assessed by FFR was 70%, 78%, 46% and 91% respectively. In patients with single vessel disease, the sensitivity, specificity, PPV and NPV were 86%, 66%, 38% and 95% respectively. The greatest discordance was seen in patients with wall thickening abnormalities (WTA) and negative FFR. During a follow up of 3.0±1.9 years there were 15 cardiovascular (CV) events. The number of wall segments with inducible WTAs emerged as the only independent predictor of CV events (HR 1.22 (1.05–1.43), p=0.01). FFR was not a predictor of outcome. There was a significant increase in event rate in patients with WTA/negative FFR and WTA/positive FFR, compared to patients with no WTA (p=0.04). However, no significant difference was seen between patients with WTA/negative FFR versus WTA/positive FFR (p=0.38) Conclusion In a patient population with significant CV risk factors, a normal SE effectively ruled out abnormal FFR. The greatest discordance was seen in patients with abnormal SE/normal FFR. In this group, patients had similar outcomes compared to those with abnormal SE/positive FFR but worse outcomes compared to patients with a normal SE. These findings have significant clinical implications.Abstract 115 Figure 1Abstract 115 Figure 2

145 Stress Echocardiography Demonstrates Excellent Feasibility, Safety and Diagnostic Accuracy in Patients with Significant Obesity: First Results from the Stress Ultrasonography in Morbid Obesity (SUMO) Study

Background Significant obesity is an increasing global health problem. Obese individuals often have a clustering of cardiovascular risk factors such as hypertension, diabetes and dyslipidaemia. Thus, symptomatic patients often have a high pre-test probability of coronary artery disease (CAD) and are frequently referred for cardiac stress testing. These patients can provide significant technical challenges for imaging due to body habitus. The feasibility, safety and accuracy of stress echocardiography in patients with morbid obesity is unknown. Methods In this prospective multi-centre study, height, weight, body mass index (BMI) and body surface area (BSA) of all patients clinically referred for SE were measured. For patients with BMI >35, patient demographics and SE test results were also collected. The feasibility of SE was defined as the ability to perform and complete the test, achieving interpretable images for all three coronary artery territories. Agreement with angiography findings in patients subsequently referred for cardiac catheterization was also evaluated. Results Over an 11 month period across 3 hospitals, 2601 patients underwent SE, by 12 different operators, of whom 170 (6.5%) had BMI >35. Mean age was 59yrs, 44% were male and 25% had known CAD. Mean BMI was 39.5 and mean BSA was 2.2 m2. Dobutamine and exercise stress were performed in 60% and 40% respectively. Ultrasound contrast was used in 96% cases. There were no complications during the SE studies. SE demonstrated excellent feasibility, with a diagnostic test result achieved in 163/170 (96%) patients. Of the 7 patients with inconclusive SE, 2 were due to side-effects from dobutamine, 2 due to failure to reach target heart rate and 3 were due to poor image quality (thus just 3/170 [2%] due to poor image quality). Of 23 patients with inducible ischaemia, 19 proceeded to angiography and 17 had corresponding significant CAD (positive predictive value 89%). Conclusions SE demonstrates excellent feasibility, safety and positive predictive value in real-world clinical practice in patients with morbid obesity. These results are clinically pertinent given the increasing proportion of such patients sent for non-invasive testing. Follow-up of this cohort to delineate event-free survival will reveal the accuracy of risk stratification of SE in this high-risk population.