Atrial systole and left ventricular filling in hypertrophic cardiomyopathy: effect of verapamil

From Atrial Fibrillation Management to Atrial Myopathy Assessment: The Evolving Concept of Left Atrium Disease in Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most prevalent genetically inherited cardiovascular disorder in adults and a significant cause of heart failure and sudden cardiac death. Historically, atrial fibrillation (AF) has been considered as a critical aspect in HCM patients as it is considered to be a marker of disease progression, escalates the frequency of heart failure hospitalisations, increases the risk of thromboembolic events, and worsens quality of life and outcome. Increasing evidence suggests that AF is the result of a subtle long-standing process that starts early in the history of HCM. The process of left atrial dilation accompanied by morphologic and functional remodelling is the quintessential prerequisite for the onset of AF. This review aims to describe the current understanding of AF pathophysiology in HCM, emphasising the role of left atrial myopathy in its development. In addition, we discuss risk factors and management strategies specific to AF in the context of HCM, providing insights into the complexities and challenges of treating this specific patient population.

First-degree atrioventricular block in hypertrophic cardiomyopathy patients: an easy and worthy prognostic marker?

Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiac disease. Recently, a connection has been observed between the presence of first-degree atrioventricular block (FDAVB) and cardiovascular outcomes, although the pathophysiology of this association remains poorly understood. Considering the period 2000-2023, we retrospectively included HCM patients at sinus rhythm at the first appointment and sought possible interactions of FDAVB (defined as PR interval >200 ms) with different clinical and imaging variables and with the occurrence of cardiovascular events, including atrial fibrillation (AF). A total of 97 patients were included, of whom 57 (58.8%) were men, with a mean age of 51±19 years, and 14 (14.4%) had FDAVB. During a median of 4.29 (P25 1.92, P75 7.67) years of follow-up, 35 cardiovascular events occurred, including 13 de novo diagnoses of AF, 8 hospitalizations due to heart failure, 8 new-onset strokes, 4 myocardial infarctions, and 2 implantations of cardio defibrillators in secondary prevention; no HCM-related death occurred. We did not find any association between outcomes and the presence of FDAVB. The role of FDAVB as a prognostic marker in HCM patients requires further investigation. We found that FDAVB patients were older, more frequently reported dyspnea, had a larger QRS duration, a higher E/e' ratio, and lower maximal left ventricle wall thickness by magnetic resonance (p<0.05). After multivariable analysis, FDAVB was independently associated with a higher echocardiographic E/e' ratio (p=0.039) (odds ratio=1.588). This is the first paper to document an independent association between FGAVB and a higher E/e' ratio in HCM patients.

Dobutamine effects on systolic and diastolic left ventricular long-axis excursion and timing - significance for the interpretation of s' and e'

BACKGROUND

Dobutamine effects on the relationships of the peak velocity of left ventricular (LV) long-axis systolic motion (s') with systolic excursion (SExc), systolic duration (SDur) and heart rate, of LV long-axis early diastolic excursion (EDExc) with SExc, and of the peak velocity of LV long-axis early diastolic motion (e') with EDExc, early diastolic duration (EDDur) and isovolumic relaxation time (IVRT') are unknown.

METHODS

Two groups of adult subjects, one young and healthy (n = 10), and one with impaired LV long-axis function (n = 10), were studied, with the aim of identifying consistent findings for the two groups and for the septal and lateral walls. Dobutamine was infused at doses of 5 and 10 µg/kg/min. The relationships between tissue Doppler imaging (TDI) variables acquired before and during dobutamine infusion were analysed using mixed effect multivariate regression modelling.

RESULTS

In both groups, heart rate increased and SDur decreased during dobutamine infusion, and there were independent inverse correlations of SDur with heart rate and dobutamine dose. In contrast, there was no change in EDDur during dobutamine infusion, and no consistent changes in IVRT' independent of heart rate. s' was positively correlated with SExc and inversely correlated with SDur, and there were positive correlations between EDExc and SExc and between e' and EDExc.

CONCLUSION

Dobutamine increases s' due to effects on both systolic excursion and duration and it increases e' due to the associated increases in systolic and early diastolic excursion. A lack of effect on diastolic times does not support the presence of a lusitropic effect of dobutamine.

Determinants of Exercise Capacity in Patients With Hypertrophic Cardiomyopathy

BACKGROUND

Reduced exercise capacity reflects symptom severity and clinical outcomes in patients with hypertrophic cardiomyopathy (HCM). The present study aimed to identify factors that may affect exercise capacity in patients with HCM.

METHODS

In 294 patients with HCM and preserved left ventricular (LV) ejection fraction, we compared peak oxygen consumption (peak VO₂) evaluated by cardiopulmonary exercise testing as a representative parameter of exercise tolerance with clinical and laboratory data, including N-terminal pro-hormone of brain natriuretic peptide (NT-proBNP), diastolic parameters on echocardiography, and the grade of myocardial fibrosis on cardiac magnetic resonance imaging (CMR).

RESULTS

Median peak VO₂, was 29.0 mL/kg/min (interquartile range [IQR], 25.0-34.0). Age (estimated β = -0.140, P < 0.001), female sex (β = -5.362, P < 0.001), NT-proBNP (β = -1.256, P < 0.001), and E/e' ratio on echocardiography (β = -0.209, P = 0.019) were significantly associated with exercise capacity. Peak VO₂ was not associated with the amount of myocardial fibrosis on CMR (mean of late gadolinium enhancement 12.25 ± 9.67%LV).

CONCLUSION

Decreased exercise capacity was associated with age, female sex, increased NT-proBNP level, and E/e' ratio on echocardiography. Hemodynamic changes and increased filling pressure on echocardiography should be monitored in this population for improved outcomes.

Stroke risk in hypertrophic cardiomyopathy patients with atrial fibrillation: a nationwide database study

Current treatment guidelines recommend anticoagulation for hypertrophic cardiomyopathy (HCM) with atrial fibrillation (AF) regardless of the CHA₂DS₂-VASc score. As aging and stroke risk factors (hypertension, diabetes mellitus) are confounders of ischemic stroke, young patients with a low stroke risk may not need anticoagulant treatment. This study aimed to determine the incidence of stroke and its risk factors in HCM patients with AF during a long-term follow-up. Using a national database, we retrospectively investigated 18,724 HCM patients from a systematic sample of 1,000,000 Taiwanese people between 1997 and 2013. The incidences of AF and stroke were estimated. Data were analyzed using Cox regression models. AF was identified in 598 patients (262 men, mean age 66.3±13.0 years) during a median follow-up of 7.0 years. The AF incidence in HCM patients was 5.83 per 1000 person-years, and the overall incidence of AF-associated stroke was 24.14 per 1000 person-years. The incidence of transient ischemic attack (TIA)/ischemic stroke varied from 20.41 to 60.55 per 1000 person-years, without proportionality to CHA₂DS₂-VASc score increase. Among patients aged <40 years, none experienced TIA/ischemic stroke. Univariate Cox regression models showed that age (p<0.001), prior TIA/ischemic stroke (p=0.02), and CHA₂DS₂-VASc score (p=0.003) were risk factors for TIA/ischemic stroke. Multivariate analysis indicated that age (hazard ratio 1.04, 95% confidence interval [CI] 1.02-1.06, p=0.001) and prior TIA/ischemic stroke (hazard ratio 2.82, 95% CI 1.27-6.25, p=0.011) were independently associated with TIA/ischemic stroke. Taiwanese patients with concomitant HCM and AF have a high stroke risk regardless of the CHA₂DS₂-VASc score. Aging is the main predictor. As the overall incidence of stroke was low in young patients, anticoagulants may not be needed in this subpopulation.

Sleep Disordered Breathing in Hypertrophic Cardiomyopathy-Current State and Future Directions

Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiomyopathy and sleep disordered breathing (SDB) is a treatable risk factor that has been seen to occur concurrently, and is known to propagate mortality and morbidity in a number of cardiovascular disease states including heart failure, and indeed hypertrophic cardiomyopathy. In this review, we summarize past studies that explored the simultaneous occurrence of HCM and SDB, and the pathophysiology of SDB in relation to heart failure, arrhythmias, cardiac ischemia and pulmonary hypertension in HCM. The current therapeutic modalities, with the effect of obstructive sleep apnea (OSA) treatment on HCM, are then discussed along with potential future directions.

Aging and the relationships between long-axis systolic and early diastolic excursion, isovolumic relaxation time and left ventricular length-Implications for the interpretation of aging effects on e`

BACKGROUND

Both the left ventricular (LV) long-axis peak early diastolic lengthening velocity (e`) and long-axis early diastolic excursion (EDExc) decrease with age, but the mechanisms underlying these decreases are not fully understood. The aim of this study was to investigate the relative contributions to aging-related decreases in e`and EDExc from LV long-axis systolic excursion (SExc), isovolumic relaxation time (IVRT, as a measure of the speed of relaxation) and LV end-diastolic length (LVEDL).

METHODS

The study group was 50 healthy adult subjects of ages 17-75 years with a normal LV ejection fraction. SExc, EDExc, e`and IVRT were measured from pulsed wave tissue Doppler signals acquired from the septal and lateral walls. Multivariate modelling was performed to identify independent predictors of EDExc and e`which were consistent for the septal and lateral walls.

RESULTS

EDExc decreased with age and the major determinant of EDExc was SExc, which also decreased with age. There was also a decrease of e`with age, and the major determinant of e`was EDExc. IVRT decreased with age and on univariate analysis was not only inversely correlated with EDExc and e`, but also with SExc. IVRT was only a minor contributor to models of EDExc which included SExc, and was an inconsistent contributor to models of e`which included EDExc. LVEDL decreased with age independent of sex and body size, and was positively correlated with SExc, EDExc and e`.

CONCLUSION

Major mechanisms underlying the decrease in e`seen during aging are the concomitant decreases in long-axis contraction and early diastolic excursion, which are in turn related in part to long-axis remodelling of the left ventricle. After adjusting for the extent of systolic and early diastolic excursion, slowing of relaxation, as reflected in prolongation of the IVRT, makes no more than a minor contribution to aging-related decreases in EDExc and e`.

Pathophysiological and therapeutic implications in patients with atrial fibrillation and heart failure

Heart failure and atrial fibrillation are common and responsible for significant mortality of patients. Both share the same risk factors like hypertension, ischemic heart disease, diabetes, obesity, arteriosclerosis, and age. A variety of microscopic and macroscopic changes favor the genesis of atrial fibrillation in patients with preexisting heart failure, altered subcellular Ca²⁺ homeostasis leading to increased cellular automaticity as well as concomitant fibrosis that are induced by pressure/volume overload and altered neurohumoral states. Atrial fibrillation itself promotes clinical deterioration of patients with preexisting heart failure as atrial contraction significantly contributes to ventricular filling. In addition, atrial fibrillation induced tachycardia can even further compromise ventricular function by inducing tachycardiomyopathy. Even though evidence has been provided that atrial functions significantly and independently of confounding ventricular pathologies, correlate with mortality of heart failure patients, rate and rhythm controls have been shown to be of equal effectiveness in improving mortality. Yet, it also has been shown that cohorts of patients with heart failure benefit from a rhythm control concept regarding symptom control and hospitalization. To date, amiodarone is the most feasible approach to restore sinus rhythm, yet its use is limited by its extensive side-effect profile. In addition, other therapies like catheter-based pulmonary vein isolation are of increasing importance. A wide range of heart failure-specific therapies are available with mixed impact on new onset or perpetuation of atrial fibrillation. This review highlights pathophysiological concepts and possible therapeutic approaches to treat patients with heart failure at risk for or with atrial fibrillation.

Atrial Fibrillation in Hypertrophic Cardiomyopathy: Diagnosis and Considerations for Management

Atrial fibrillation is common in hypertrophic cardiomyopathy with a prevalence of 22-32 %. The impact of atrial fibrillation on overall survival, left ventricular function, thromboembolic stroke and quality of life is crucial. This review enlightens incidence, pathophysiology, and clinical symptoms. Early recognition of atrial fibrillation is essential. Monitoring methods for early detection are described. Finally effective therapy options are discussed including oral anticoagulation and the role of interventional catheter-based ablation in the treatment of atrial fibrillation in HCM patients.

Impact of atrial fibrillation on the clinical course of apical hypertrophic cardiomyopathy

BACKGROUND

Apical hypertrophic cardiomyopathy (ApHCM) is considered a 'benign' form of hypertrophic cardiomyopathy, with limited data on the long-term outcome. However, the clinical impact of atrial fibrillation (AF) in ApHCM is largely unknown. The hypothesis was that AF is common and has a prognostic implication in ApHCM.

METHODS

The occurrence of AF and outcome was assessed in 306 consecutive patients with ApHCM (68% male, 62±11 years).

RESULTS

AF occurred in 77 patients with ApHCM (prevalence, 25.2%; annual incidence, 4.6%/year) and was independently predicted by old age and large left atrium (>45 mm). Among 70 AF patients indicated with anticoagulation, 53 patients (76%) received warfarin. During a follow-up of 5.5±2.0 years, the patients with AF had a higher incidence of all-cause death, cardiovascular death and strokes (11.7% vs 1.3%, 6.5% vs 0.9% and 19.5% vs 2.6%, respectively, all p<0.05) than those without AF. When adjusted by the age and gender, those with AF still had an increased risk for all-cause death (HR 6.58; 95% CI 1.65-26.16, p=0.007) and strokes (HR 5.13; 95% CI 1.85 to 14.18, p=0.002). AF was detected before the time of stroke in 8 (53%) out of 15 patients with both AF and stroke. In addition, six out of eight patients were on anticoagulation at the time of stroke. The cause of death was a stroke in three (33%) out of nine patients with AF.

CONCLUSION

In patients with ApHCM, AF was common and was associated with a substantial risk for strokes and mortality suggesting that AF should be carefully managed in ApHCM.

Congestive heart failure with normal ejection fraction

Clinicians must remain undaunted when history, physical examination, and chest radiography suggest congestive heart failure but left ventricular systolic function is normal. Many of these patients have diastolic dysfunction, and standard therapy for left ventricular systolic dysfunction is often ineffectual or detrimental. Noninvasive testing is subject to many pitfalls but may confirm a clinical suspicion and provide indications to treat or to proceed with invasive testing. In the absence of clinical signs and symptoms of congestive failure, however, abnormal diastolic indexes should not be interpreted as diagnostic of diastolic dysfunction and are not an indication to treat.

Inositol-1,4,5-trisphosphate induced Ca2+ release and excitation-contraction coupling in atrial myocytes from normal and failing hearts

KEY POINTS

Impaired calcium (Ca(2+)) signalling is the main contributor to depressed ventricular contractile function and occurrence of arrhythmia in heart failure (HF). Here we report that in atrial cells of a rabbit HF model, Ca(2+) signalling is enhanced and we identified the underlying cellular mechanisms. Enhanced Ca(2+) transients (CaTs) are due to upregulation of inositol-1,4,5-trisphosphate receptor induced Ca(2+) release (IICR) and decreased mitochondrial Ca(2+) sequestration. Enhanced IICR, however, together with an increased activity of the sodium-calcium exchange mechanism, also facilitates spontaneous Ca(2+) release in form of arrhythmogenic Ca(2+) waves and spontaneous action potentials, thus enhancing the arrhythmogenic potential of atrial cells. Our data show that enhanced Ca(2+) signalling in HF provides atrial cells with a mechanism to improve ventricular filling and to maintain cardiac output, but also increases the susceptibility to develop atrial arrhythmias facilitated by spontaneous Ca(2+) release.

ABSTRACT

We studied excitation-contraction coupling (ECC) and inositol-1,4,5-triphosphate (IP3)-dependent Ca(2+) release in normal and heart failure (HF) rabbit atrial cells. Left ventricular HF was induced by combined volume and pressure overload. In HF atrial myocytes diastolic [Ca(2+)]i was increased, action potential (AP)-induced Ca(2+) transients (CaTs) were larger in amplitude, primarily due to enhanced Ca(2+) release from central non-junctional sarcoplasmic reticulum (SR) and centripetal propagation of activation was accelerated, whereas HF ventricular CaTs were depressed. The larger CaTs were due to enhanced IP3 receptor-induced Ca(2+) release (IICR) and reduced mitochondrial Ca(2+) buffering, consistent with a reduced mitochondrial density and Ca(2+) uptake capacity in HF. Elementary IP3 receptor-mediated Ca(2+) release events (Ca(2+) puffs) were more frequent in HF atrial myoctes and were detected more often in central regions of the non-junctional SR compared to normal cells. HF cells had an overall higher frequency of spontaneous Ca(2+) waves and a larger fraction of waves (termed arrhythmogenic Ca(2+) waves) triggered APs and global CaTs. The higher propensity of arrhythmogenic Ca(2+) waves resulted from the combined action of enhanced IICR and increased activity of sarcolemmal Na(+)-Ca(2+) exchange depolarizing the cell membrane. In conclusion, the data support the hypothesis that in atrial myocytes from hearts with left ventricular failure, enhanced CaTs during ECC exert positive inotropic effects on atrial contractility which facilitates ventricular filling and contributes to maintaining cardiac output. However, HF atrial cells were also more susceptible to developing arrhythmogenic Ca(2+) waves which might form the substrate for atrial rhythm disorders frequently encountered in HF.

Advances in medical treatment of hypertrophic cardiomyopathy

We reviewed the natural history of patients with hypertrophic cardiomyopathy (HCM). The effect of medical treatments on natural history, left ventricular (LV) functions and LV remodeling was also evaluated. Sudden cardiac death and end-stage heart failure are the most serious complications of HCM. Age <30 years and a family history of sudden premature death are risk factors for sudden cardiac death in HCM patients. End-stage heart failure is not a specific additional phenomenon observed in patients with HCM, but is the natural course of the disease in most of those patients. After the occurrence of heart failure, the progression to cardiac death is very rapid. Young age at diagnosis, a family history of HCM, and greater wall thickness are associated with a greater likelihood of developing end-stage heart failure. Neither beta-blockers nor calcium antagonists can prevent this transition. The class Ia antiarrhythmic drugs, disopyramide and cibenzoline are useful for the reduction of LV pressure gradient. Unlike disopyramide, cibenzoline has little anticholinergic activity; therefore, this drug can be easily adapted to long-term use. In addition to the reduction in LV pressure gradient, cibenzoline can improve LV diastolic dysfunction, and induce regression of LV hypertrophy in patients with HCM. A decrease in intracellular Ca(2+) concentration through the activation of the Na(+)/Ca(2+) exchanger associated with cibenzoline therapy is likely to be closely related with the improvement in HCM-related disorders. It is possible that cibenzoline can prevent the progression from typical HCM to end-stage heart failure.

Radiofrequency catheter ablation of the accessory pathway adversely affected the left ventricular outflow tract pressure gradient in a patient with hypertrophic obstructive cardiomyopathy

Although hypertrophic cardiomyopathy (HCM) with an accessory pathway is encountered in clinical practice, there is little evidence of a coherent strategy for ablation of the accessory pathway in patients with HCM. We present the case of a 61-year-old man who had type B Wolff-Parkinson-White (WPW) syndrome with hypertrophic obstructive cardiomyopathy (HOCM). Due to paroxysmal atrial fibrillation, he underwent radiofrequency catheter ablation of the accessory pathway located in the right postero-lateral wall to prevent secondary symptomatic events. His LV dyssynchrony improved after the procedure, but the degree of the LV outflow tract (LVOT) pressure gradient was increased. To stabilize the LVOT pressure gradient, he needed additional medications. This case shows that patients with HOCM should be carefully evaluated before making a decision concerning ablation of the accessory pathway.

Pharmacological treatment options for hypertrophic cardiomyopathy: high time for evidence

Hypertrophic cardiomyopathy (HCM) is the most common genetic heart disease, affecting over one million individuals in Europe. Hypertrophic cardiomyopathy patients often require pharmacological intervention for control of symptoms, dynamic left ventricular outflow obstruction, supraventricular and ventricular arrhythmias, and microvascular ischaemia. Current treatment strategies in HCM are predicated on the empirical use of long-standing drugs, such as beta-adrenergic and calcium blockers, although with little evidence supporting their clinical benefit in this disease. In the six decades since the original description of the disease, <50 pharmacological studies enrolling little over 2000 HCM patients have been performed, the majority of which were small, non-randomized cohorts. As our understanding of the genetic basis and pathophysiology of HCM improves, the availability of transgenic and preclinical models uncovers clues to novel and promising treatment modalities. Furthermore, the number of patients identified and followed at international referral centres has grown steadily over the decades. As a result, the opportunity now exists to implement adequately designed pharmacological trials in HCM, using established as well as novel drug therapies, to potentially intervene on the complex pathophysiology of the disease and alter its natural course. Therefore, it is timely to review the available evidence for pharmacological therapy of HCM patients, highlight the most relevant gaps in knowledge, and address some of the most promising areas for future pharmacological research, in an effort to move HCM into the era of evidence-based management.

Hypertrophic Cardiomyopathy in a Young Adult with RV Aneurysm: Report of a Rare Finding and Review of the Literature

We report a case of a 22-year-old patient with a severe form of hypertrophic cardiomyopathy involving both ventricles, for which he underwent surgical treatment. Echocardiogram and magnetic resonance imaging confirmed the presence of an aneurysm in the inferior-anterior portion of the right ventricle.

Interactions between sleep disordered breathing and atrial fibrillation in patients with hypertrophic cardiomyopathy

The aim of this study was to investigate whether patients with hypertrophic cardiomyopathy (HC) and sleep disordered breathing (SDB) have a higher prevalence of atrial fibrillation (AF) compared to patients with HC without SDB. HC is associated with a high prevalence of AF that contributes to increased morbidity and mortality. SDB is strongly associated with a higher incidence, prevalence, and recurrence of AF in patients without HC. Whether this association also applies to patients with HC is not known. Overnight oximetry was prospectively performed on 91 consecutive patients with echocardiographically confirmed HC. The presence or absence of AF in this population was correlated with the oximetric findings. SDB was associated with a higher prevalence of AF (40% vs 11%, p = 0.005). In addition, SDB was accompanied by significantly increased left atrial volume index (58 +/- 19 vs 42 +/- 13 ml/m(2), p = 0.0002). Increasing severity of SDB was correlated with higher AF prevalence and with increase in left atrial volume index. These associations remained significant even after accounting for potential confounders in a multivariate analysis. In conclusion, these findings suggest that the presence and severity of SDB may influence left atrial volume index and the prevalence of AF in patients with HC. SDB may therefore be an important and potentially modifiable cause of morbidity and mortality in this population.

Atrial Fibrillation in Hypertrophic Obstructive Cardiomyopathy - Antiarrhythmics, Ablation and More!

Hypertrophic cardiomyopathy (HCM) is a genetic disease of the cardiac sarcomere with an autosomal dominant pattern of inheritance. Patients with HCM are at high risk of developing atrial fibrillation (AF) particularly in the setting of advanced diastolic dysfunction and left atrial enlargement. AF is a marker of increased mortality and morbidity and results in a significant reduction in quality of life. Antiarrhythmic medications improve symptoms and reduce AF recurrence, but few are safe and there exists little data to guide their long-term use in HCM. Non-pharmacologic approaches have emerged and have equal or greater efficacy than pharmacologic approaches. Although these approaches are promising, the long-term impact on atrial function needs to be carefully studied as it may impact quality of life in patients that age in the setting of a progressive diastolic disease disorder. Nonetheless, with the significant impact of AF in HCM, rhythm control strategies are often required. The understanding of rhythm control strategies in HCM, an often rapidly progressive diastolic dysfunction disorder, may provide insight in how to treat the much more prevalent AF patient with hypertensive cardiomyopathy. Regardless of treatment strategy (rhythm or rate control) patients are a moderate to high risk of thromboembolism and until data are available to suggest otherwise require long-term warfarin anticoagulation.

Transesophageal pulsed Doppler echocardiographic evaluation of left atrial systolic performance in hypertrophic cardiomyopathy: combined analysis of transmitral and pulmonary venous flow velocities

BACKGROUND

Hypertrophic cardiomyopathy (HC) is characterized by impaired left ventricular (LV) diastolic function due to an increase in LV wall thickness. The severity of this disease varies depending on the localization and extent of the hypertrophied myocardium and the presence and extent of myocardial disarray or fibrosis.

HYPOTHESIS

The purpose of this study was to examine the background of hemodynamic abnormalities between the left atrium and the left ventricle during atrial systole in patients with HC using pulsed Doppler echocardiography.

METHODS

Hemodynamic abnormalities between the left atrium and left ventricle during atrial systole were evaluated in patients with HC using transmitral flow (TMF) and pulmonary venous flow (PVF) velocities obtained by transesophageal pulsed Doppler echocardiography. The study population included 50 patients with HC, including 39 with asymmetric septal hypertrophy and 11 with apical hypertrophy, and showing fractional shortening of the left ventricle > or = 30%. They were classified into three groups: (1) Group A (n = 11): the ratio of the late to early TMF velocity < 1, and peak atrial systolic PVF velocity (PVA) < 25 mm/s; (2) Group B (n = 13): their ratio < 1, and PVA > or = 25 mm/s; and (3) Group C (n = 26): their ratio > or = 1. The mean age of patients in Group A was lower than that in Groups B and C.

RESULTS

Left atrial dimension in Group B was significantly greater than that in the other HC groups and the control group. Furthermore, left atrial volume changes during atrial systole in Group B were significantly smaller than those in the other HC groups and the control group. Peak atrial systolic PVF velocity in Group B was significantly higher than that in the control group and in Group C. The duration of the atrial systolic waves of the TMF and PVF in Group B was significantly shorter and longer, respectively, than that in Group A. Left ventricular end-diastolic pressure (LVEDP) decreased in descending order with Group B > Group C > Group A. In all patients there was a significant positive correlation between the LVEDP and peak atrial systolic PVF velocity or the difference in duration between the atrial systolic waves of PVF and TMF. Plots of these values shifted toward the left and inferiorly in Group A, and toward the right and superiorly in Group B.

CONCLUSION

Peak velocity and duration of TMF and PVF during atrial systole by transesophageal pulsed Doppler echocardiography are useful indices of hemodynamic abnormalities between the left atrium and the left ventricle during atrial systole, particularly a forceful atrial contraction mismatched to the left atrial afterload and severity of LV diastolic dysfunction, in HC.

Prognostic significance of exercise induced arrhythmias and echocardiographic variables in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HC) often presents with exercise-induced symptoms, including arrhythmias and sudden death. The investigators prospectively studied whether exercise testing is associated with immediate complications and if stress-induced arrhythmias and echocardiographic variables are associated with long-term adverse outcomes. Exercise echocardiography with 6-channel continuous monitoring for arrhythmias was performed in consecutive patients with HC clinically referred for the test. End points included death, myocardial infarction, revascularization, stroke, atrial fibrillation, ventricular tachycardia, and myectomy. Of 86 patients with HC (mean age 56.6 +/- 16.1 years) who underwent exercise echocardiography, arrhythmias occurred in 39 (45%), including 23 (27%) with premature atrial contractions, 2 (2%) with atrial fibrillation, 28 (33%) with premature ventricular contractions (16 also had atrial arrhythmias), and 1 (1.2%) with nonsustained ventricular tachycardia (hemodynamically stable). During a follow-up of 2.6 +/- 2.8 years, major events occurred in 11 patients (3 deaths, 5 revascularizations, 3 strokes). In addition, 12 patients developed atrial fibrillation, 6 developed nonsustained ventricular tachycardia, and 13 underwent myectomies. Variables associated with major events included hypertension, male gender, and worsening wall motion score index with exercise; increased exercise duration was associated with fewer events. ST-T changes on baseline electrocardiography and premature ventricular contractions were associated with atrial fibrillation risk. In conclusion, in this cohort of patients with HC, exercise testing was safe. Test results were associated with risk for adverse events.

First-pass myocardial perfusion defect and delayed contrast enhancement in hypertrophic cardiomyopathy assessed with MRI

BACKGROUND

Gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) enhanced magnetic resonance imaging (MRI) is known to be useful for detecting myocardial injury. In this study, we used first-pass myocardial perfusion and delayed contrast-enhanced MRI to determine whether an abnormal signal intensity was related to the left ventricular regional contractile function in patients with hypertrophic cardiomyopathy (HCM).

MATERIALS AND METHODS

Twelve patients with HCM participated in this study. Four short axial cine images of the left ventricle were acquired. Subsequently, first-pass myocardial perfusion images during the first passage of Gd-DTPA (0.1 mmol/kg), and delayed contrast-enhanced images after a 15-min delay, were acquired in the same orientation as cine imaging. Each image was divided into eight blocks and a total of 384 blocks were analyzed.

RESULTS

First-pass myocardial perfusion defects (PD) were detected in nine patients with an average of 11.5+/-11 blocks. Delayed contrast enhancement (DE) was detected in 11 patients with an average of 11.5+/-10 blocks. Mean wall thickness in PD blocks (16.7+/-4.7 mm) was larger than that in normal perfusion blocks (13.6+/-3.9 mm, p<0.001). Mean wall thickness in DE blocks (16.9+/-4.9 mm) was larger than that in normal enhanced blocks (13.4+/-3.6 mm, p<0.001). PD were located at almost the same site as DE, but DE areas were larger than PD areas (p=0.0021). Mean percent wall thickening of blocks with PD (63.1+/-44.7%, p<0.0001) and blocks with DE (75.2+/-81.5%, p<0.01) was lower than that in blocks with neither PD nor DE (103.5+/-66.0%). Significant correlations were found between percent wall thickening and percent PD (r=0.46, p<0.0001) and between percent wall thickening and percent DE (r=0.54, p<0.0001).

CONCLUSION

Abnormal signal intensity from first-pass myocardial perfusion and delayed contrast-enhanced MRI are closely related to left ventricular regional contractile function.

Tissue Doppler-Derived Indices Predict Exercise Capacity in Patients With Apical Hypertrophic Cardiomyopathy

BACKGROUND

Although impaired left ventricular (LV) diastolic function is a prominent feature of hypertrophic cardiomyopathy (HCM), diastolic function and its relation to exercise capacity in apical HCM (ApHCM) has not been explored previously. This study was sought to determine the relationship between diastolic mitral annular velocities combined with conventional Doppler indexes and exercise capacity in patients with ApHCM.

PATIENTS

Twenty-nine patients with ApHCM (24 men; mean age +/- SD, 57 +/- 10 years) underwent supine bicycle exercise with simultaneous respiratory gas analysis and two-dimensional and Doppler echocardiographic study.

RESULTS

The mitral inflow velocities (early filling [E], late filling, and deceleration time) were traced and measured. Early diastolic mitral annular velocity (E') was measured at the septal corner of mitral annulus by Doppler tissue imaging (DTI) from the apical four-chamber view. Pro-brain natriuretic peptide (proBNP) was measured at the time of echocardiography using a quantitative electrochemiluminescence immunoassay. E/E' ratio correlated inversely with maximal oxygen uptake (Vo(2)max) [r = - 0.47, p = 0.0106]. There was a significant positive correlation between E' and Vo(2)max (r = 0.41, p = 0.024). However, no correlation was found between conventional two-dimensional, Doppler indices, and proBNP and Vo(2)max). Of all the echocardiographic and clinical parameters assessed, E/E' ratio had the best correlation with exercise capacity (r - 0.47) and was the strongest independent predictor of Vo(2)max by multivariate analysis (p = 0.0106).

CONCLUSIONS

DTI-derived indexes (E', E/E' ratio), an estimate of myocardial relaxation and LV filling pressures, correlate with exercise capacity in patients with ApHCM, suggesting that abnormal diastolic function may be a factor limiting exercise capacity.

Is Functional Capacity Related to Left Atrial Contractile Function in Nonobstructive Hypertrophic Cardiomyopathy?

The mechanisms underlying reduced exercise capacity in patients with nonobstructive hypertrophic cardiomyopathy (NHCM) could include perturbations of ventricular relaxation, diastolic compliance, or compensatory atrial systolic function. We hypothesized that a loss of atrial contractility in NHCM patients leads to reduced functional capacity. To test this hypothesis, we compared resting noninvasive left atrial ejection phase indices in 49 consecutive patients with NHCM (ages 36+/-10 years; 41% female) and normal left ventricular ejection fraction (mean, 68%+/-8%) with objective metabolic exercise parameters. Left atrial active emptying fraction, ejection force, and kinetic energy failed to predict exercise capacity. Only left atrial total and active emptying volumes correlated weakly with minute volume/CO2 production slope (r=0.31 and r=0.33; p<0.05 for both). Furthermore, when subjects were stratified by New York Heart Association symptomatology, exercise parameters--but not atrial contractility--differed between groups. These data, obtained at rest, fail to suggest that NHCM-related heart failure symptoms are due to an atrial myopathy.

Determinant of left atrial dilation in patients with hypertrophic cardiomyopathy: A real-time 3-dimensional echocardiographic study

To identify the determinants of left atrial (LA) dilation for patients with hypertrophic obstructive cardiomyopathy (HOCM), first we validated LA volume determination by real-time 3-dimensional echocardiography using magnetic resonance imaging in patients. Subsequently, real-time 3-dimensional echocardiography and 2-dimensional Doppler echocardiography were performed in 60 patients with HOCM and in 17 age-matched control subjects. LA volumes and left ventricular (LV) filling pressures were higher for patients with HOCM than in control subjects. By stepwise multilinear regression analysis, LV end-diastolic pressure, resting LV outflow tract pressure gradient, and LV wall thickness were significant determinants of LA dilation. However, tau, -dP/dt, LV stiffness, provokable pressure gradient, and mitral regurgitation did not have any independent relationship with LA volumes. Therefore, it is concluded that LA volume can be accurately determined by real-time 3-dimensional echocardiography; and LA dilation in patients with HOCM is related to LV filling pressure, LV outflow tract pressure gradient, and LV wall thickness.

Intra- and interatrial conduction delay: implications for cardiac pacing

Atrial conduction disorders are frequent in elderly subjects and/or those with structural heart diseases, mainly mitral valve disease, hyperthrophic cardiomyopathies, and hypertension. The resultant electrophysiological and electromechanical abnormalities are associated with a higher risk of paroxysmal or persistent atrial tachyarrhythmias, either atrial fibrillation, typical or atypical flutter or other forms of atrial tachycardias. Such an association is not fortuitous because intra- and interatrial conduction abnormalities delays disrupt (spatial and temporal dispersion) electrical activation, thus promoting the initiation and perpetuation of reentrant circuits. Preventive therapeutic interventions induce variable, sometimes paradoxical effects as with the proarrhythmic effect of class I antiarrhythmic drugs. Similarly, atrial pacing may promote proarrhythmias or an antiarrhythmic effect according to the pacing site(s) and mode. Multisite atrial pacing was conceived to correct, as much as possible, abnormal activation induced by spontaneous intra- or interatrial conduction disorders or by single site atrial pacing, which are situations responsible for commonly refractory arrhythmias. Atrial electrical resynchronization can also be used to correct mechanical abnormalities like left heart AV dyssynchrony resulting from intraatrial conduction delays.

Left atrial volume and the risk of paroxysmal atrial fibrillation in patients with hypertrophic cardiomyopathy

Paroxysmal atrial fibrillation (PAF) is a common complication of patients with hypertrophic cardiomyopathy, often leading to acute or progressive heart failure and cerebral infarction. We assessed the echocardiographic data of 141 consecutive patients with hypertrophic cardiomyopathy, with and without PAF. In all, 31 patients (22%) had a history of PAF with spontaneous conversion to in sinus rhythm. Left atrial volume and left atrial volume indexed to body surface area were significantly increased for patients with PAF compared with those without PAF. Maximum left atrial volume was the most sensitive and specific parameter for the occurrence of PAF in patients with hypertrophic cardiomyopathy.

HYPERHOMOCYSTEINAEMIA-INDUCED ATRIAL REMODELLING IN HYPERTENSIVE RATS

Studies from our laboratory and others indicate that, in addition to its purported atherothrombotic effects, hyperhomocysteinaemia (Hhe) is a powerful stimulus for ventricular remodelling, dysfunction and clinical heart failure. Because changes in atrial structure and function can impact on cardiac function in progressive ventricular remodelling and dysfunction, we conducted experiments to examine structural and functional remodelling of the atria in the hyperhomocysteinaemic hypertensive rat, a previously described model of ventricular diastolic dysfunction. Atrial muscle preparations were isolated from hearts of spontaneously hypertensive rats that were fed control, intermediate Hhe-inducing or severe Hhe-inducing diet for 10 weeks. Atrial developed tension, +dT/dt(max) and -dT/dt(max) were found to increase in parallel with levels of Hhe and ventricular diastolic dysfunction. Post-rest developed tension and the maximum developed tension observed in the presence of isoproterenol were also increased significantly in both Hhe groups compared with control. These results indicate that Hhe increases both basal and maximal contractile function in atrial muscle. Atrial structural remodelling was characterized by increased interstitial fibrosis in both Hhe groups. These data suggest that Hhe-associated changes in atrial structure and function may act to maintain ventricular filling in Hhe-induced diastolic dysfunction.

Left ventricular diastolic function assessed using Doppler tissue imaging in patients with hypertrophic cardiomyopathy: relation to symptoms and exercise capacity

BACKGROUND

Conventional Doppler indices of left ventricular diastolic function do not correlate with symptoms or exercise capacity in patients with hypertrophic cardiomyopathy, because of their dependence on loading conditions. Diastolic mitral annular velocity measured using Doppler tissue imaging has been reported to be a preload independent index of left ventricular diastolic function.

OBJECTIVE

To determine the relation between diastolic annular velocities combined with conventional Doppler indices and symptoms or exercise capacity in hypertrophic cardiomyopathy.

METHODS

85 patients with hypertrophic cardiomyopathy and 60 normal controls were studied. Diastolic mitral annular velocities, transmitral left ventricular filling, and pulmonary venous velocities were measured.

RESULTS

Early diastolic velocities at lateral and septal annulus were lower in patients with hypertrophic cardiomyopathy than in controls (lateral Ea: 10 (3) v 18 (4) cm/s, p < 0.0001; septal Ea: 7 (2) v 12 (3) cm/s, p < 0.0001). Unlike conventional Doppler indices alone, transmitral early left ventricular filling velocity (E) to lateral Ea ratio correlated inversely with peak oxygen consumption (r = -0.42, p < 0.0001). Patients in New York Heart Association (NYHA) class III had a higher transmitral E to lateral Ea ratio (12.0 (4.6)) than those in NYHA class II (7.6 (3.1), p < 0.005) or class I (6.6 (2.6), p < 0.0001).

CONCLUSIONS

Early diastolic mitral annular velocities are reduced in patients with hypertrophic cardiomyopathy. Unlike conventional Doppler indices alone, the transmitral E to lateral Ea ratio correlates with NYHA functional class and exercise capacity.

[Myocardial perfusion SPECT and isotopic ventriculography in obstructive and non-obstructive hypertrophic myocardiopathy]

OBJECTIVE

To evaluate the role of myocardial perfusion SPET and radionuclide ventriculography in patients with hypertrophic cardiomyopathy (HC).

METHODS

Exercise myocardial perfusion SPET with 99mTc-tetrofosmin and radionuclide ventriculography were performed in a consecutive series of 101 patients (54 15 years, 50 women, 55 with dynamic obstruction) diagnosed of HC by echo. Follow-up from the diagnosis was 9,9 6,7 years (1 to 28 years).

RESULTS

Thirty six percent of patients had perfusion defects (non reversible in 15 and reversible in 21). In non obstructive HC higher number of patients with non reversible defects (p = 0.01 was obseved and in patients with no reversible defects higher incidence of pathologic Q waves in ECG (p = 0.01), Higher ventricular volumes (p < 0.05), lower ejection fraction (p = 0,0001) and longer time to peak emptying velocity (p < 0.05). There were 4 cardiac deaths, 15 syncopes, 18 pacemakers and 6 myectomy. Ejection fraction was higher in patients with syncope (p = 0,034) and there was no isotopic variable predictive of mortality, pacemaker or myectomy.

CONCLUSIONS

Neither SPET nor radionuclide ventriculography have a prognostic role in patients with HC, but patients with syncope have higher values of ejection fraction. Patients with non reversible defects have higher rate of pathologic Q waves in ECG, higher ventricular volumes and lower ejection fraction. This is indicative of evolution to dilated form of HC.

Impact of atrial fibrillation on the clinical course of hypertrophic cardiomyopathy

BACKGROUND

Clinical impact of atrial fibrillation (AF) in hypertrophic cardiomyopathy (HCM) is largely unresolved. Thus, we analyzed the prognostic implications of AF in a large, community-based HCM population assembled from Italian and US cohorts.

METHODS AND RESULTS

Occurrence of AF and outcome were assessed in 480 consecutive HCM patients (age at diagnosis, 45+/-20 years; 61% male) who were followed up for 9.1+/-6.4 years. AF occurred in 107 patients (22%; incidence, 2%/y) and was independently predicted by advancing age, congestive symptoms, and increased LA size at diagnosis. Patients with AF had increased risk for HCM-related death (OR, 3.7; P<0.002) because of excess heart failure-related mortality but not sudden, unexpected death. This risk associated with AF was substantially greater in patients with outflow obstruction or with earlier development of AF (</=50 years of age). AF patients were also at increased risk for stroke (OR, 17.7; P=0.0001) and severe functional limitation (OR for NYHA class III or IV, 2.8; P<0.0001). Compared with those with exclusively paroxysmal AF, patients developing chronic AF showed higher combined probability of HCM-related death, functional impairment, and stroke (P<0.0001). In a subgroup of 37 patients with AF (35%), the clinical course was largely benign in the absence of stroke and severe symptoms.

CONCLUSIONS

In a community-based HCM population, AF (1) was common, with 22% prevalence over 9 years; (2) was associated with substantial risk for heart failure-related mortality, stroke, and severe functional disability, particularly in patients with outflow obstruction, those </=50 years of age, or those developing chronic AF; and (3) was nevertheless compatible with benign outcome in 35% of patients.

[Therapeutic approaches in symptomatic hypertrophic obstructive cardiomyopathy]

Hypertrophic cardiomyopathy is a complex and heterogeneous disease. Although most patients experience just a few symptoms, and have a good prognosis, there are others whose symptoms are severe and progressive, determined by different pathophysiological elements such as diastolic dysfunction, myocardial ischemia, arrhythmias and subaortic obstruction. Approximately 20-30% of hypertrophic cardiomyopathy patients develop an intraventricular dynamic gradient, which in some cases, is responsible for severe symptoms which are ameliorated once the obstruction is reduced. In many cases the symptoms can be controlled with medical treatment which includes betablockers, calcium-channel antagonists and dysopiramide, but some patients will still experience severe and refractory symptoms. This subgroup of patients, which represent approximately 5-10% of patients with hypertrophic cardiomyopathy, can be problematic from a management perspective. For many years, septal myectomy and/or mitral valve replacement offered the only effective alternative therapy for these patients. However, the high rates of morbidity and mortality associated with these procedures have necessitated the search for new and less invasive procedures such as ventricular pacing and percutaneous septal ablation. Although the initial results with sequential pacing were encouraging, further studies have suggested a significant placebo effect, which makes its application controversial. In the last 5 years selective embolization of the septal artery precipitating a localized myocardial infarction has been utilized to reduce the subaortic gradient. The potential indications and efficacy of these new forms of treatment, like ventricular pacing and percutaneous septal ablation, are presently under evaluation and are the main subject of this review. Medical treatment, with either beta-blockers, calcium channel antagonists or dysopiramide constitutes the first therapeutic step. Surgery, while alleviating the subaortic obstruction and reducing the intraventicular pressure and mitral insufficiency, produces important and long-lasting symptomatic and functional improvement in most of these patients, and it continues to be an important therapeutic alternative in these cases. If the first results with sequential pacemaker implants were encouraging, today it is alluded to an important placebo effect that causes its application to be controversial. In the last 5 years the path has been made in the creation of a septal infarction located through the embolization of the septal branches to reduce the gradient.

Does the progression of myocardial fibrosis lead to atrial fibrillation in patients with hypertrophic cardiomyopathy?

The majority of left ventricular (LV) inflow volumes in hypertrophic cardiomyopathy (HCM) depend on atrial contraction because of impaired LV relaxation. If HCM is complicated by atrial fibrillation (AF), heart failure can develop because of the loss of atrial contraction. The purpose of this study was to determine the relationship between the development of AF and myocardial fibrosis or intramyocardial small artery (IMSA) stenosis in autopsied hearts with HCM. Studies were performed in five HCM hearts with AF (AF group) and five HCM hearts without AF (non-AF group). LV specimens were divided into the inner (IT), middle (MT), and outer (OT) thirds. We selected at random 120 fields and 20 IMSAs from each layer and assessed them quantitatively using an image analyzer. We determined the extent of fibrosis (%F) and the degree of stenosis of each IMSA (%L). The %F in the AF group was greater than in the non-AF group (P<.01). In the AF group, the %F of the IT was greater than in the MT and the OT (P<.01). In the non-AF group, the %F of the IT was greater than in the MT (P<.05), and the %F of the MT was greater than in the OT (P<.01). The %L was similar in the AF and non-AF groups. In both groups, the %L of the IT was lower than in the MT (P<.01), which was lower than that of the OT (P<.05). LV fibrosis is more severe in patients with HCM and AF than in those without AF. Therefore, myocardial fibrosis might impair LV relaxation, resulting in hemodynamic intolerance to AF.

Clinical significance of atrial fibrillation in hypertrophic cardiomyopathy

Atrial fibrillation (AF) is the most common sustained arrhythmia in patients with hypertrophic cardiomyopathy (HCM), and it bears numerous pathophysiologic consequences that potentially affect patient outcome and symptoms. However, studies regarding the impact of AF on the long-term prognosis of HCM patients have been limited in number, with sometimes conflicting results. Recently, studies on community-based patient populations showed that AF is associated with long-term clinical deterioration, embolic complications, and increased cardiovascular mortality due to heart failure and stroke. The consequences of AF on the long-term prognosis of HCM patients are not uniformly unfavorable, however, and in about one third of patients the arrhythmia is compatible with an uneventful course.

Prediction of mean pulmonary wedge pressure using doppler pulmonary venous flow variables in hypertrophic cardiomyopathy

We examined whether pulmonary venous flow variables, assessed by transthoracic Doppler echocardiography, could predict mean pulmonary wedge pressure in hypertrophic cardiomyopathy. Forty-four patients with no left ventricular systolic dysfunction (left ventricular fractional shortening > or =25%) were studied. Forty patients with systolic dysfunction (dilated cardiomyopathy group) served as control. Mitral and pulmonary venous flow velocity curves were recorded with the pulsed-Doppler method and were related to mean pulmonary wedge pressure obtained by right heart catheterization. In hypertrophic cardiomyopathy group, the systolic (r=-0.15, P=0.335) and diastolic (r=0.35, P=0.022) forward flow velocity were poorly related to mean pulmonary wedge pressure, whereas the velocity of atrial reversal (r=0.68, P<0.001) correlated well with mean pulmonary wedge pressure. In dilated cardiomyopathy group, the systolic (r=-0.51, P=0.001) and diastolic (r=0.60, P<0.001) forward flow velocity were strongly related to mean pulmonary wedge pressure. With the cut-off value set at the velocity of atrial reversal >30 cm/s in hypertrophic cardiomyopathy group, the sensitivity for predicting mean pulmonary wedge pressure >15 mmHg was 79% and the specificity was 73%. In conclusion, the atrial component of the pulmonary venous flow can be used to predict mean pulmonary wedge pressure in hypertrophic cardiomyopathy.

Left atrial systolic function is depressed in idiopathic and preserved in ischemic dilated cardiomyopathy

BACKGROUND

Left atrial systolic dysfunction, unexplained by altered loading conditions, has been reported in idiopathic dilated cardiomyopathy suggesting left atrial involvement in the myopathic process.

MATERIALS AND METHODS

Seventeen patients with idiopathic dilated cardiomyopathy, 16 with ischemic dilated cardiomyopathy and 18 normal controls were studied with transthoracic echocardiography and cardiac catheterization. Transmitral diastolic flow was evaluated with pulsed Doppler. Left atrial volume (cm3/m2) at mitral valve opening (maximal, Vmax.), onset of atrial systole (P wave of the electrocardiogram, Vp), and mitral valve closure (minimal, Vmin. ) was determined with two-dimensional echocardiography using the biplane area-length method. The left atrial active emptying fraction (ACTEF = [Vp-Vmin.] x 100/Vp) served as an index of systolic function.

RESULTS

The peak early diastolic transmitral flow velocity (cm/sec) was similar in the three groups (idiopathic: 60 +/- 16, ischemic: 58 +/- 20, control: 56 +/- 22; P = NS), whereas the late diastolic transmitral flow velocity was lower but not significantly different in idiopathic compared to ischemic cardiomyopathy, and in both was lower than control (26 +/- 12 vs. 34 +/- 13 vs. 44 +/- 14, respectively; P < 0.05). Vmax. and Vp were similar in idiopathic and ischemic cardiomyopathy and greater than control (44.6 +/- 13.6 vs. 48.2 +/- 18.3 vs. 26.9 +/- 6.2; P < 0.05, and 34.6 +/- 13.4 vs. 30.8 +/- 10.9 vs. 16.7 +/- 3.7, respectively; P < 0.05). ACTEF was lower in idiopathic than in ischemic cardiomyopathy and in the latter it was similar to control (18 +/- 10% vs. 32 +/- 10% vs. 36 +/- 10%, respectively; P < 0.05). Moreover, ACTEF was inversely related to left atrial tension at end-of atrial systole both in idiopathic and in ischemic cardiomyopathy (r2 = 0.52, P = 0.001 and r2 = 0.57, P = 0.0007, respectively). However, at any given level of left atrial tension at end of atrial systole, ACTEF was lower in idiopathic than ischemic cardiomyopathy.

CONCLUSION

Left atrial systolic function is depressed in idiopathic and preserved in ischemic dilated cardiomyopathy despite similar left atrial loading conditions. This finding suggests left atrial myopathy in the former, and may be related to the differences in the response to medical treatment and clinical outcome observed between the two conditions.

Hypertrophic cardiomyopathy: MR measurement of coronary blood flow and vasodilator flow reserve in patients and healthy subjects

PURPOSE

To evaluate coronary blood flow per gram of myocardial mass and vasodilator flow reserve in patients with hypertrophic cardiomyopathy (HCM) and in healthy subjects by using breath-hold velocity-encoded cine (VEC) magnetic resonance (MR) imaging.

MATERIALS AND METHODS

Twenty-nine patients with HCM and nine healthy volunteers were examined. Fast VEC MR images were obtained in an oblique imaging plane perpendicular to the coronary sinus before and after intravenous injection of dipyridamole (0.56 mg/kg). The products of mean velocity and cross-sectional area of the vessel were integrated to measure blood flow. Breath-hold cine MR images encompassing the entire left ventricle were acquired to quantify the left ventricular mass.

RESULTS

In the basal state, the coronary blood flow per gram of myocardial mass was 0.74 mL/min/g +/- 0.23 in healthy subjects and 0.62 mL/min/g +/- 0.27 in patients with HCM. After administration of dipyridamole, coronary blood flow in patients with HCM increased to a level significantly less than that in healthy subjects (1.03 mL/min/g +/- 0.40 vs 2.14 mL/min/g +/- 0.51; P < .01), resulting in a severely depressed flow reserve ratio in patients with HCM compared with that in healthy subjects (1.72 +/- 0.49 vs 3.01 +/- 0.75; P < .01).

CONCLUSION

Breath-hold VEC MR imaging is a noninvasive technique for evaluating coronary flow per gram of myocardial mass and coronary flow reserve.