AQUA Mutant Protein Quantification of Endomyocardial Biopsy-Sized Samples From a Patient With Hypertrophic Cardiomyopathy

In genetic diseases like hypertrophic cardiomyopathy, reliable quantification of the expression level of mutant protein can play an important role in disease research, diagnosis, treatment and prognosis. For heterozygous β-myosin heavy chain (β-MyHC) mutations it has been shown that disease severity is related to the fraction of mutant protein in the myocardium. Yet, heart tissue from patients with genetically characterized diseases is scarce. Here we asked, if even in the case of small endomyocardial biopsies, single quantifications produce reliable results. Myocardial samples were taken from four different regions of an explanted heart of a patient with hypertrophic cardiomyopathy carrying point mutation p.Gly716Arg in β-MyHC. From both, large samples (15 mg) and small, endomyocardial biopsy-sized samples (≤ 1 mg) myosin was extracted and enzymatically digested to yield a specific peptide of interest that allowed to distinguish mutant and wild-type β-MyHC. Absolute quantification by mass spectrometry (AQUA) of the peptide of interest was performed repeatedly for both sample sizes to determine the fraction of mutant β-MyHC. Fractions of mutant β-MyHC (32% on average) showed only small differences between the four cardiac regions and for large and small samples. The standard deviations were smaller than five percentage points for all cardiac regions. The two quantification methods (large and small sample size) produce results with comparable accuracy and precision. Consequently, with our method even small endomyocardial biopsies allow reliable protein quantification for potential diagnostic purposes.

Burst-Like Transcription of Mutant and Wildtype MYH7-Alleles as Possible Origin of Cell-to-Cell Contractile Imbalance in Hypertrophic Cardiomyopathy

Hypertrophic Cardiomyopathy (HCM) has been related to many different mutations in more than 20 different, mostly sarcomeric proteins. While development of the HCM-phenotype is thought to be triggered by the different mutations, a common mechanism remains elusive. Studying missense-mutations in the ventricular beta-myosin heavy chain (β-MyHC, MYH7) we hypothesized that significant contractile heterogeneity exists among individual cardiomyocytes of HCM-patients that results from cell-to-cell variation in relative expression of mutated vs. wildtype β-MyHC. To test this hypothesis, we measured force-calcium-relationships of cardiomyocytes isolated from myocardium of heterozygous HCM-patients with either β-MyHC-mutation Arg723Gly or Arg200Val, and from healthy controls. From the myocardial samples of the HCM-patients we also obtained cryo-sections, and laser-microdissected single cardiomyocytes for quantification of mutated vs. wildtype MYH7-mRNA using a single cell RT-qPCR and restriction digest approach. We characterized gene transcription by visualizing active transcription sites by fluorescence in situ hybridization of intronic and exonic sequences of MYH7-pre-mRNA. For both mutations, cardiomyocytes showed large cell-to-cell variation in Ca⁺⁺-sensitivity. Interestingly, some cardiomyocytes were essentially indistinguishable from controls what might indicate that they had no mutant β-MyHC while others had highly reduced Ca⁺⁺-sensitivity suggesting substantial fractions of mutant β-MyHC. Single-cell MYH7-mRNA-quantification in cardiomyocytes of the same patients revealed high cell-to-cell variability of mutated vs. wildtype mRNA, ranging from essentially pure mutant to essentially pure wildtype MYH7-mRNA. We found 27% of nuclei without active transcription sites which is inconsistent with continuous gene transcription but suggests burst-like transcription of MYH7. Model simulations indicated that burst-like, stochastic on/off-switching of MYH7 transcription, which is independent for mutant and wildtype alleles, could generate the observed cell-to-cell variation in the fraction of mutant vs. wildtype MYH7-mRNA, a similar variation in β-MyHC-protein, and highly heterogeneous Ca⁺⁺-sensitivity of individual cardiomyocytes. In the long run, such contractile imbalance in the myocardium may well induce progressive structural distortions like cellular and myofibrillar disarray and interstitial fibrosis, as they are typically observed in HCM.

Intrinsic MYH7 expression regulation contributes to tissue level allelic imbalance in hypertrophic cardiomyopathy

HCM, the most common inherited cardiac disease, is mainly caused by mutations in sarcomeric genes. More than a third of the patients are heterozygous for mutations in the MYH7 gene encoding for the β-myosin heavy chain. In HCM-patients, expression of the mutant and the wildtype allele can be unequal, thus leading to fractions of mutant and wildtype mRNA and protein which deviate from 1:1. This so-called allelic imbalance was detected in whole tissue samples but also in individual cells. There is evidence that the severity of HCM not only depends on the functional effect of the mutation itself, but also on the fraction of mutant protein in the myocardial tissue. Allelic imbalance has been shown to occur in a broad range of genes. Therefore, we aimed to examine whether the MYH7-alleles are intrinsically expressed imbalanced or whether the allelic imbalance is solely associated with the disease. We compared the expression of MYH7-alleles in non-HCM donors and in HCM-patients with different MYH7-missense mutations. In the HCM-patients, we identified imbalanced as well as equal expression of both alleles. Also at the protein level, allelic imbalance was determined. Most interestingly, we also discovered allelic imbalance and balance in non-HCM donors. Our findings therefore strongly indicate that apart from mutation-specific mechanisms, also non-HCM associated allelic-mRNA expression regulation may account for the allelic imbalance of the MYH7 gene in HCM-patients. Since the relative amount of mutant mRNA and protein or the extent of allelic imbalance has been associated with the severity of HCM, individual analysis of the MYH7-allelic expression may provide valuable information for the prognosis of each patient.

Optimized pacing mode for hypertrophic cardiomyopathy: Impact of ECG fusion during pacing

BACKGROUND

Electrocardiographic (ECG) fusion with intrinsic QRS could reduce the benefit of atrial synchronous biventricular pacing (AS-BiVP) in patients with hypertrophic obstructive cardiomyopathy (HOCM).

OBJECTIVES

The purpose of this study was to assess the benefit of AS-BiVP and the influence of ECG fusion for reduction of left ventricular outflow tract gradient (LVOTG) in these patients.

METHODS

Twenty-one symptomatic HOCM patients with severe LVOTG were included. Twelve patients were evaluated retrospectively for the prevalence of fusion and its influence on outcomes after AS-BiVP. Eleven patients (2 of the first population were also evaluated retrospectively) were prospectively included to evaluate the benefit of performing atrioventricular node ablation (AVNA) to achieve full ventricular capture if fusion was present during AS-BiVP.

RESULTS

Seven of the first 12 patients (58%) had ECG fusion. After 54 ± 24 months of AS-BiVP, the presence of fusion was associated with lower values for reduction of resting, dynamic LVOTG and New York Heart Association (NYHA) class. In the prospectively evaluated patients, after 12 months of follow-up, resting LVOTG decreased from 98 ± 39 to 39 ± 24 mm Hg (P = .008); dynamic LVOTG decreased from 112 ± 38 to 60 ± 24 mm Hg (P = .013); NYHA class decreased from 2.8 ± 0.4 to 1.7 ± 0.6 (P = .014); endurance time during constant work rate cycling exercise (80% of peak oxygen consumption) increased from 399 ± 148 to 691 ± 249 seconds (P = .046); quality of life improved from 46 ± 22 to 22 ± 20 points (P = .02); and brain natriuretic peptide levels decreased from 318 ± 238 to 152 ± 118 pg/mL (P = .09). Eight of the 11 prospectively evaluated patients (73%) needed AVNA, which further decreased LVOTG from 108 ± 40 mm Hg at baseline to 89 ± 29 mm Hg after BiVP to 54 ± 22 mm Hg after AVNA (P = .003).

CONCLUSION

As-BiVP that ensures no ECG fusion, by means of AVNA when needed, appears to be the optimal pacing mode in HOCM patients.

Familial hypertrophic cardiomyopathy: functional effects of myosin mutation R723G in cardiomyocytes

Familial Hypertrophic Cardiomyopathy (FHC) is frequently caused by mutations in the β-cardiac myosin heavy chain (β-MyHC). To identify changes in sarcomeric function triggered by such mutations, distinguishing mutation effects from other functional alterations of the myocardium is essential. We previously identified a direct effect of mutation R723G (MyHC723) on myosin function in slow Musculus soleus fibers. Here we investigate contractile features of left ventricular cardiomyocytes of FHC-patients with the same MyHC723-mutation and compare these to the soleus data. In mechanically isolated, triton-permeabilized MyHC723-cardiomyocytes, maximum force was significantly lower but calcium-sensitivity was unchanged compared to donor. Conversely, MyHC723-soleus fibers showed significantly higher maximum force and reduced calcium-sensitivity compared to controls. Protein phosphorylation, a potential myocardium specific modifying mechanism, might account for differences compared to soleus fibers. Analysis revealed reduced phosphorylation of troponin I and T, myosin-binding-protein C, and myosin-light-chain 2 in MyHC723-myocardium compared to donor. Saturation of protein-kinaseA phospho-sites led to comparable, i.e., reduced MyHC723-calcium-sensitivity in cardiomyocytes as in M. soleus fibers, while maximum force remained reduced. Myofibrillar disarray and lower density of myofibrils, however, largely account for reduced maximum force in MyHC723-cardiomyocytes. The changes seen when phosphorylation of sarcomeric proteins in myocardium of affected patients is matched to control tissue suggest that the R723G mutation causes reduced Ca(++)-sensitivity in both cardiomyocytes and M. soleus fibers. In MyHC723-myocardium, however, hypophosphorylation can compensate for the reduced calcium-sensitivity, while maximum force generation, lowered by myofibrillar deficiency and disarray, remains impaired, and may only be compensated by hypertrophy.

Unequal allelic expression of wild-type and mutated β-myosin in familial hypertrophic cardiomyopathy

Familial hypertrophic cardiomyopathy (FHC) is an autosomal dominant disease, which in about 30% of the patients is caused by missense mutations in one allele of the β-myosin heavy chain (β-MHC) gene (MYH7). To address potential molecular mechanisms underlying the family-specific prognosis, we determined the relative expression of mutant versus wild-type MYH7-mRNA. We found a hitherto unknown mutation-dependent unequal expression of mutant to wild-type MYH7-mRNA, which is paralleled by similar unequal expression of β-MHC at the protein level. Relative abundance of mutated versus wild-type MYH7-mRNA was determined by a specific restriction digest approach and by real-time PCR (RT-qPCR). Fourteen samples from M. soleus and myocardium of 12 genotyped and clinically well-characterized FHC patients were analyzed. The fraction of mutated MYH7-mRNA in five patients with mutation R723G averaged to 66 and 68% of total MYH7-mRNA in soleus and myocardium, respectively. For mutations I736T, R719W and V606M, fractions of mutated MYH7-mRNA in M. soleus were 39, 57 and 29%, respectively. For all mutations, unequal abundance was similar at the protein level. Importantly, fractions of mutated transcripts were comparable among siblings, in younger relatives and unrelated carriers of the same mutation. Hence, the extent of unequal expression of mutated versus wild-type transcript and protein is characteristic for each mutation, implying cis-acting regulatory mechanisms. Bioinformatics suggest mRNA stability or splicing effectors to be affected by certain mutations. Intriguingly, we observed a correlation between disease expression and fraction of mutated mRNA and protein. This strongly suggests that mutation-specific allelic imbalance represents a new pathogenic factor for FHC.

The left and right ventricle of a patient with a R723G mutation of the beta-myosin heavy chain and severe hypertrophic cardiomyopathy show no differences in the expression of myosin mRNA

BACKGROUND

In familial hypertrophic cardiomyopathy (FHC), asymmetric left ventricular (LV) hypertrophy has been considered to be the predominant phenotypic expression, whereas right ventricular (RV) involvement is still ambiguous. In most cases, the right ventricle remains unaffected until secondary pulmonary hypertension develops. Several FHC-causing mutations of genes encoding sarcomere-related proteins have been identified which are transmitted in an autosomal-dominant manner.

METHODS

We report the case of a 61 year old member of a Catalan family with a Arg723Gly missense mutation of the β-myosin heavy chain (β-MHC), that is associated with a malignant phenotype characterized by sudden cardiac death and heart failure. Because of progressive systolic LV dysfunction, the patient received a heart transplant in 2003.

RESULTS

Molecular analysis of the myocardial tissue of the explanted heart, taken from the left and right ventricle, showed a similar deviation of the ratio of mutant vs wild type mRNA of the β-MHC of 71.8 ± 5% and 68.5 ± 3%, respectively. This finding was confirmed for LV biopsies of this patient on protein level, showing a similar proportion of mutated β-myosin. But since the patient is heterozygous for the β-MHC mutation and the mutation is located in a coding region, the relative increase of the expression of the mutant allele is unexpected. It has been demonstrated before by our group for several β-MHC mutations that the relative abundance of mutated mRNA/protein correlates with the clinical severity of the disease. But since the right ventricle shows no (or only minor) manifestation in terms of hypertrophy or dysfunction, the level of mRNA and protein expression is not the only factor responsible for the development of the phenotype of FHC.

CONCLUSIONS

Several mechanisms through which cardiac stresses may incite maladaptive cardiac remodeling primarily of the left ventricle that result in myocardial hypertrophy and heart failure are proposed. One of those triggers could be the enhanced work load of the left ventricle, especially if a LV outflow tract gradient is present, in contrast to the lesser demands to the right ventricle which is adapted to the low pressure system of the pulmonary circulation. Further studies are needed to confirm the results of this case, as well as functional studies involving both ventricles.

Quantification of mutant versus wild-type myosin in human muscle biopsies using nano-LC/ESI-MS

A liquid chromatography/electrospray ionization mass spectrometry (nano-LC/ESI-MS) approach is described by which abundance of proteins (e.g., of beta-myosin heavy chain; MW 223 kDa) carrying a point mutation can be determined in tissue samples where the mutant protein is coexpressed with its wild-type forms. After enzymatic cleavage of the extracted parent protein, mutant and wild-type species of the peptide with the locus of the point mutation were quantified. Synthetic peptides, identical to wild-type and mutant peptides but labeled with stable isotopes ((13)C, (15)N), were added in known amounts as internal standards. The peak areas obtained by MS for the stable-isotope-labeled peptides and for the native peptides were used for quantification. To demonstrate the suitability of this approach we determined the relative abundance of beta-myosin with the Arg723Gly exchange in muscle biopsies of patients with Familial Hypertrophic Cardiomyopathy (HCM). For two such patients the fraction of mutated myosin was 62%, i.e., significantly different from 50%, which is quite unexpected for an autosomal dominant disease in heterozygous patients. Correlation between abundance of mutant myosin and clinical malignancy seen for several mutations in the myosin head domain emphasizes the relevance of such quantification. The approach for quantification described here is generally applicable for quantification of proteins with single point mutations even if only small amounts of tissue are available.

[Clinical and echocardiographic follow-up of patients with hypertrophic obstructive cardiomyopathy treated by percutaneous septal ablation]

INTRODUCTION AND OBJECTIVES

Alcohol septal ablation is a therapeutic option for patients with hypertrophic obstructive cardiomyopathy who remain symptomatic despite medical treatment. Our aim was to monitor clinical and echocardiographic progression in patients with hypertrophic obstructive cardiomyopathy treated by septal ablation at our center.

METHODS

Thirty-five septal ablations were performed in 34 patients (79% male) who had symptomatic hypertrophic obstructive cardiomyopathy despite optimum medical treatment. The procedure was successful in 32 (i.e., the reduction in left ventricular outflow tract pressure gradient, or LVOTPG, was >50%). During clinical and echocardiographic follow-up, New York Heart Association (NYHA) functional class and LVOTPG were monitored.

RESULTS

The patients' mean age was 63 (12) years. The mean follow-up period was 9 (3) months. Immediately after septal ablation, LVOTPG decreased significantly, from 74.2 (25.3) mm Hg to 26 (25) mm Hg (P<.001), and remained low throughout follow-up. Moreover, echocardiography showed that the interventricular septum thickness also decreased during follow-up, from 19 (3) mm to 15 (2) mm (P<.0001). A significant improvement in NYHA functional class (from 93% in class III-IV to 84% in class I-II) was also observed. Two deaths occurred within 48 hours after the procedure. The most frequent complication was complete heart block (20%; n=6).

CONCLUSIONS

Alcohol septal ablation is effective in patients with hypertrophic obstructive cardiomyopathy who remain symptomatic despite medical treatment. However, the procedure is associated with a significant rate of complications and should, therefore, be reserved for selected patients, in particular for elderly patients and those with comorbid conditions.

Hypertrophic cardiomyopathy-related beta-myosin mutations cause highly variable calcium sensitivity with functional imbalances among individual muscle cells

Disease-causing mutations in cardiac myosin heavy chain (beta-MHC) are identified in about one-third of families with hypertrophic cardiomyopathy (HCM). The effect of myosin mutations on calcium sensitivity of the myofilaments, however, is largely unknown. Because normal and mutant cardiac MHC are also expressed in slow-twitch skeletal muscle, which is more easily accessible and less subject to the adaptive responses seen in myocardium, we compared the calcium sensitivity (pCa(50)) and the steepness of force-pCa relations (cooperativity) of single soleus muscle fibers from healthy individuals and from HCM patients of three families with selected myosin mutations. Fibers with the Arg723Gly and Arg719Trp mutations showed a decrease in mean pCa(50), whereas those with the Ile736Thr mutation showed slightly increased mean pCa(50) with higher active forces at low calcium concentrations and residual active force even under relaxing conditions. In addition, there was a marked variability in pCa(50) between individual fibers carrying the same mutation ranging from an almost normal response to highly significant differences that were not observed in controls. While changes in mean pCa(50) may suggest specific pharmacological treatment (e.g., calcium antagonists), the observed large functional variability among individual muscle cells might negate such selective treatment. More importantly, the variability in pCa(50) from fiber to fiber is likely to cause imbalances in force generation and be the primary cause for contractile dysfunction and development of disarray in the myocardium.

[Late T-lymphocyte and monocyte activation in coronary restenosis. Evidence for a persistent inflammatory/immune mechanism?]

AIMS

This study was made to determine if restenosis after percutaneous coronary angioplasty is associated with acute or chronic inflammatory/immunologic activity, and explored possible relationships with latent infection.

PATIENTS AND METHOD

Forty-six consecutive patients underwent elective PTCA and 6 months of angiographic follow-up. Peripheral venous blood samples were obtained at baseline, 24-48 h, and 4-6 months post-intervention. Flow-cytometric methods were used to measure early and late circulating leukocyte activation status. Il-6 and TNF-alpha cytokines, and Il-2 soluble receptor concentrations were determined in all plasma samples. Chlamydia pneumoniae and Cytomegalovirus antibody assays were performed to detect infectious disease.

RESULTS

Angiographic coronary stenosis developed in 27 out of 46 patients. At 6 months of follow-up, these patients showed a significant increase in circulating cytotoxic T-lymphocytes CD3+/CD56+ (18.8 7.1 vs 6.12 2.7%; p = 0.005) and activated monocytes (CD11b: 1,383 624 vs 990 484 MFI, p = 0.025; CD64: 76.0 28.7 vs 56.7 21.8 MFI; p = 0.014), with no apparent relation to increased cytokines or latent infectious disease.

CONCLUSIONS

Restenosis appears to be associated to inflammatory and immunological activity that persists 6 months after coronary intervention. No relationship was found with the infections studied. The presence of inflammatory activity 4-6 months after PTCA suggess that pharmacological therapeutic interventions to prevent restenosis should be maintained for months.

Utility of ambulatory 24-hour esophageal pH and motility monitoring in noncardiac chest pain: report of 90 patients and review of the literature

It is unclear whether prolonged motility monitoring improves the diagnostic yield of standard esophageal tests in patients with noncardiac chest pain. Our aim was to assess the diagnostic value of ambulatory 24-hr pH and pressure monitoring in patients with noncardiac chest pain. Stationary manometry, edrophonium testing, and ambulatory pH and motility studies were performed in 90 consecutive patients with recurrent chest pain and normal coronary angiograms. Normality limits of ambulatory 24-hr motility were established in 30 healthy controls. The diagnoses of specific esophageal motility disorders (nutcracker esophagus and diffuse esophageal spasm) by stationary and ambulatory manometry were discordant in 48% of the patients. Edrophonium testing was positive in 9 patients, but correlated poorly with esophageal diagnoses. During ambulatory studies, 144 chest pain events occurred in 42 patients, and 72 (50%) were related to esophageal dysfunction. Strict temporal associations of events with esophageal dysfunction in relation to ambulatory 24-hr pH/motility scores permitted four patient categorizations: true positives (event-related and abnormal tests), N = 15; true negatives (event-unrelated and abnormal tests), N = 10; reduced esophageal pain threshold (event-related and normal tests), N = 4; and indeterminate origin (event-unrelated and normal tests), N = 13. Overall, 19 patients (21%) had a probable esophageal cause for chest pain (14 esophageal motility disorder, 4 acid reflux, 1 both). In conclusion, ambulatory manometry increases the diagnostic yield of standard esophageal testing in noncardiac chest pain, but the gain is small. Causes of chest pain other than high esophageal pressures and acid reflux must still be sought in most patients with chest pain of unknown origin after a negative cardiac work-up.

Malignant hypertrophic cardiomyopathy caused by the Arg723Gly mutation in beta-myosin heavy chain gene

Mutations causing hypertrophic cardiomyopathy have been described in nine genes encoding sarcomeric proteins. We report a new mutation in three families, with a C-->G transversion in nucleotide 12 307 of the beta-myosin heavy chain gene, located at the essential light chain interacting region, resulting in the replacement of arginine by glycine at amino acid residue 723. PCR amplification of the selected regions followed by single strand conformation polymorphism analysis, DNA sequencing of the polymorphic patterns and restriction analysis were used to detect the mutation. A total of 23 individuals were diagnosed as carriers, and seven were obligate carriers or had been clinically diagnosed. The Arg723Gly mutation was associated with a malignant phenotype. Ten out of 30 affected members died suddenly or needed an implantable cardioverter-defibrillator at a mean age of 42, and seven members developed progressive heart failure, leading to death or heart transplant in five, at a mean age of 50 years. Echocardiography showed non-obstructive left ventricular hypertrophy in affected members older than 20 (sensitivity 68%). Mean survival of affected members was 51 years. In conclusion, a new mutation Arg723Gly in beta-myosin heavy chain gene is reported which shortens life expectancy because of sudden death and end-stage heart failure.

Association Between TGF-β Gene Polymorphism and Left Ventricular Hypertrophy in Essential Hypertension

P61

The aim of the study was to evaluate the possible association between two TGF-β1 gene polymorphisms and left ventricular hypertrophy in a group of essential hypertensive patients (EH). Ninety-three non treated EH underwent 24-hour ambulatory blood pressure, two-dimensional guided M-mode echocardiography in order to measure left ventricular mass index (LVMI), and TGF-β1 Leu 10 /Pro and Arg 25 /Pro polymorphism genotyping. As shown in the table, 24-h SBP and DBP were significantly higher in homozygous patients for the Arg 25 allele of the TGF-β1 gene. Likewise, homozygous patients for the Leu 10 allele and homozygous patients for the Arg 25 allele of the TGF-β1 gene had significanlty higher LVMI. We conclude that these TGF-β1 gene polymorphisms are associated with the severity of blood pressure and left ventricular hypertrophy in EH patients.

Lack of association between ACE gene polymorphism and left ventricular hypertrophy in essential hypertension

The possible association between the insertion/deletion (I/D) polymorphism of the angiotensin I converting enzyme (ACE) gene and left ventricular hypertrophy (LVH) was investigated in a group of essential hypertensive patients. Seventy-one essential hypertensive patients (35 men and 36 women), aged 51 +/- 1 years, were genotyped by PCR for the I/D polymorphism of the ACE gene. Cardiac morphology and function were assessed by means of M-mode echocardiography. The relative frequencies of the three genotypes, DD, DI, and II, were respectively: 24%, 55%, and 21%. Mean values of left ventricular mass index were 145, 144, and 150 g/m2 for DD, DI, and II genotypes, without significant differences among them (P = 0.82). Likewise, the prevalence of LVH (76%, 64%, and 87%) was not significantly different among the three genotypes (P = 0.23). We conclude that the ACE gene I/D polymorphism is not associated with LVH in essential hypertension. Journal of Human Hypertension (2000) 14, 47-49.

Myocardial uptake of antimyosin antibody in idiopathic dilated cardiomyopathy and its relation to functional and morphological parameters

Monoclonal 111In antimyosin (AMS) uptake indicates the presence of ongoing myocyte damage. In idiopathic dilated cardiomyopathy (IDC), there is diffuse myocyte damage. We have attempted to find a correlation between AMS uptake and functional myocardial parameters. With this purpose in mind, we studied two groups of subjects: group 1 comprised 19 subjects with IDC and group 2 comprised 6 control subjects. In all subjects, an antimyosin scan was performed. Among the subjects with IDC, two-dimensional echocardiography was carried out to determine the left ventricular ejection fraction (LVEF) and left ventricular dimensions, and a gated blood pool study was undertaken to assess the LVEF at rest and end-diastolic and end-systolic volumes. Three months later, repeat antimyosin scintigraphy and equilibrium gated blood pool were performed on 13 of the patients. The mean heart to lung (H/L) ratio in the IDC subjects was 1.82 +/- 0.25 (range 1.42-2.25), a value significantly higher than that obtained in the controls: 1.41 +/- 0.12 (range 1.26-1.58) (P < 0.001). Linear regression analysis did not find a statistically significant correlation between H/L and gated blood pool or echocardiography measures. No marked changes in ejection fraction and antimyosin uptake were found between baseline and follow-up studies. Subjects with IDC have a high incidence of positive antimyosin scans, but antimyosin uptake is not related to any functional or morphological parameters.

[The predictive value of ventricular function during exercise after a myocardial infarct]

To assess the prognostic value of exercise left ventricular function, and if this test improves the prognostic value of clinical data and exercise test, 146 patients (mean age 56 +/- 9 years) underwent rest and exercise radionuclide angiography, 10 days after myocardial infarction. During follow-up (mean 16 +/- 5 months), 32 patients had new coronary events: 5 died, 9 had a new myocardial infarction and the remaining 18 developed unstable angina (Class III-IV of the CCS classification). Patients with new coronary events had more frequently severe left ventricular failure (Killip III-IV) (15% vs 3%; p less than 0.05) and postinfarction angina (32% vs 9%; p less than 0.01) than their counterparts. There were no differences regarding rest ejection fraction between both groups of patients. Exercise ejection fraction increased significantly (50 +/- 14% to 56 +/- 16%, p less than 0.001), while there was no change in patients with new coronary events (46 +/- 16% to 43 +/- 15%, NS). Logistic regression analysis including only clinical data identified postinfarction angina (p less than 0.01) and left ventricular failure (Killip III-IV) (p less than 0.01) as independent predictors of new coronary events. The sensitivity and specificity of the regression equation obtained with clinical data were 43% and 90%, respectively. Analyzing data from clinical variables, as well as exercise test and both, rest and exercise radionuclide angiography, logistic regression analysis identified, exercise ejection fraction (p less than 0.001), postinfarction angina (p less than 0.01) and rest ejection fraction (p less than 0.05) as independent predictors of new coronary events.(ABSTRACT TRUNCATED AT 250 WORDS)