Inclusion of electric disturbance type cardiomyopathy in the classification of cardiomyopathy: A current review

More than 50 Years after Konno's Development of the Endomyocardial Biopsy

The endomyocardial biopsy (EMB) method was first developed by Japan's Dr. Souji Konno in 1962. Since then, this technique has been used worldwide in clinical cardiology for the recognition and diagnosis of cardiomyopathies, arrhythmias, and other heart conditions. Many studies relating to the EMB have been published at the global level, including a large review by Cooper, et al.,¹⁾ wherein a limited selection of Japanese papers were cited despite considerable pioneering work on the EMB having been done in Japan. Following this, the Cardiac Biopsy Conference (CABIC) organization, which was founded in Japan in 1979, conducted a nationwide survey of the English language literature on the EMB. Among the collection of 500 studies compiled, approximately 40 abstracts have been selected by the co-editors in CABIC for further discussion. This report aims to supplement Cooper's work and bring to light other prominent contributions of Japanese researchers on the EMB.

Is surgery the gold standard in the treatment of obstructive hypertrophic cardiomyopathy?

OBJECTIVES

Hypertrophic cardiomyopathy is a complex and relatively common genetic cardiac disease and has been the subject of intensive scrutiny and investigation for over 40 years. The aim of this non-randomized cohort study was to compare subjective and objective outcomes in hypertrophic cardiomyopathy patients undergoing drug therapy, surgical myotomy-myectomy, dual-chamber pacing and alcohol septal ablation.

METHODS

We examined 194 patients: 103 with non-obstructive hypertrophic cardiomyopathy and 91 with obstructive hypertrophic cardiomyopathy. All the patients with a non-obstructive form were on drug therapy. Ninety-one consecutive patients with drug-refractory obstructive hypertrophic cardiomyopathy were treated invasively. Dual-chamber pacemaker implantation was performed for 49 patients with previous positive temporary pacing test (Group 1). In 28 patients with massive left ventricle hypertrophy and obliteration of its cavities, extensive myotomy-myectomy was performed (Group 2). In 14 patients with midventricular obstruction and appropriate coronary anatomy, alcohol septal ablation was performed (Group 3).

RESULTS

The peak left ventricle outflow tract gradient was 84.1 ± 15.2 mmHg in Group 1, 113.3 ± 14.9 mmHg in Group 2 and 97.5 ± 8.9 mmHg in Group 3. Dual-chamber pacing in Group 1 with optimal atrio-ventricular delay (85-180 ms for atrium pacing and 45-120 ms for atrial sensing) leads to dramatic decreases in left ventricle outflow tract gradient to 17.6 ± 11.8 mmHg and degree of mitral regurgitation. After extensive myectomy in Group 2, we observed a reduction of left ventricle outflow tract gradient to 17.3 ± 10.2 mmHg. Septal alcohol ablation in Group 3 leads to a left ventricle outflow tract gradient decrease from 97.5 ± 8.9 to 25.3 ± 5.8 mmHg.

CONCLUSIONS

Surgical myectomy, dual-chamber pacing and alcohol septal ablation are equally effective in reducing obstruction in case of correct indications. Dual-chamber pacing is indicated in functional reversible states characterized by excitation delay. Alcohol septal ablation is preferable in cases with midventricular obstruction and appropriate coronary anatomy. Surgical methods are indicated in anatomical irreversible changes and remain the gold standard for obstructive hypertrophic cardiomyopathy treatment.

Lamin A/C gene mutations in familial cardiomyopathy with advanced atrioventricular block and arrhythmia

Lamin A and C proteins, encoded by the lamin A/C gene (LMNA), are inner nuclear membrane proteins predominantly expressed in terminally differentiated cells. Mutations in LMNA can cause various forms of cardiomyopathy with arrhythmia in an autosomal dominant manner. We collected and evaluated the clinical characteristics of unclassified familial cardiomyopathy with advanced AV block and sporadic cases with advanced AV block. Mutation in LMNA was directly screened using the cycle sequencing method in 5 probands of the familial cardiomyopathy and 60 sporadic cases with advanced AV block. In four of the five familial cases (80%), we identified four distinct mutations: two protein-truncation mutations, R225X and 815_818delinsCCAGAC, and two missense mutations, Y259H and R166P. No sporadic cases carried LMNA mutation. Left ventricular end-diastolic diameter (LVEDD) was slightly enlarged in LMNA mutant carriers (123.5 +/- 9.5%) as well as in non-carriers (125.1 +/- 13.3%), while left ventricular fractional shortening (LVFS) was preserved in LMNA mutant carriers (32.3 +/- 4.8%) and non-carriers (37.6 +/- 6.8%). In LMNA mutation carriers, the average age at onset of advanced AV block is significantly lower than that in non-carriers (43.7 +/- 9.5 vs. 65.3 +/- 13 yr., p < 0.01). Ventricular tachycardia, sudden death, and poor prognosis were observed in LMNA mutation carriers. LMNA mutation could cause familial cardiomyopathy with insignificant LV remodeling, early-age onset of advanced AV block, and lethal ventricular arrhythmia. Screening of LMNA mutation might be beneficial for risk stratification and clinical management of this type of unclassified familial cardiomyopathy.