Use of implantable pacemakers and implantable defibrillators in hypertrophic cardiomyopathy

Pacing for drug-refractory or drug-intolerant hypertrophic cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is a genetic disease with an autosomal-dominant inheritance for which negative inotropes are the most widely used initial therapies. Observational studies and small randomised trials have suggested symptomatic and functional benefits using pacing and several theories have been put forward to explain why. Pacing, although not the primary treatment for HCM, could be beneficial to patients with relative or absolute contraindications to surgery or alcohol ablation. Several randomised controlled trials comparing pacing to other therapeutic modalities have been conducted but no Cochrane-style systematic review has been done.

OBJECTIVES

To assess the effects of pacing in drug-refractory or drug-intolerant hypertrophic cardiomyopathy patients.

SEARCH METHODS

We searched the following on the 14/4/2010: CENTRAL (The Cochrane Library 2010, Issue 1), MEDLINE OVID (from 1950 onwards ), EMBASE OVID (from 1980 onwards ), Web of Science with Conference Proceedings (from 1970 onwards). No language restrictions were applied.

SELECTION CRITERIA

Randomised controlled trials of either parallel or crossover design that assess the beneficial and harmful effects of pacing for hypertrophic cardiomyopathy were included. When crossover studies were identified, we considered data only from the first phase.

DATA COLLECTION AND ANALYSIS

Data from included studies were extracted onto a pre-formed data extraction paper by two authors independently. Data was then entered into Review Manager 5.1 for analysis. Risk of bias was assessed using the guidance provided in the Cochrane Handbook. For dichotomous data, relative risk was calculated; and for continuous data, the mean differences were calculated. Where appropriate data were available, meta-analysis was performed. Where meta-analysis was not possible, a narrative synthesis was written. A QUROUM flow chart was provided to show the flow of papers.

MAIN RESULTS

Five studies (reported in 10 papers) were identified. However, three of the five studies provided un-usable data. Thus the data from only two studies (reported in seven papers) with 105 participants were included for this review. There was insufficient data to compare results on all-cause mortality, cost effectiveness, exercise capacity, Quality of life and Peak O2 consumption.When comparing active pacing versus placebo pacing on exercise capacity, one study showed that exercise time decreased from (13.1 ± 4.4) minutes to (12.6 ± 4.3) minutes in the placebo group and increased from (12.1 ± 5.6) minutes to (12.9 ± 4.2) minutes in the treatment group (MD 0.30; 95% CI -1.54 to 2.14). Statistically significant data from the same study showed that left ventricular outflow tract obstruction decreased from (71 ± 32) mm Hg to (52 ± 34) mm Hg in the placebo group and from (70 ± 24) mm Hg to (33 ± 27) mm Hg in the active pacing group (MD -19.00; 95% CI -32.29 to -5.71). This study was also able to show that New York Heart Association (NYHA) functional class decreased from (2.5 ± 0.5) to (2.2 ± 0.6) in the inactive pacing group and decreased from (2.6 ± 0.5) to (1.7 ± 0.7) in the placebo group (MD -0.50; 95% CI -0.78 to -0.22).When comparing active pacing versus trancoronary ablation of septal hypertrophy (TASH), data from one study showed that NYHA functional class decreased from (3.2 ± 0.7) to (1.5 ± 0.5) in the TASH group and decreased from (3.0 ± 0.1) to (1.9 ± 0.6) in the pacemaker group. This study also showed that LV wall thickness remained unchanged in the active pacing group compared to reduction from (22 ± 4) mm to (17 ± 3) mm in the TASH group (MD 0.60; 95% CI -5.65 to 6.85) and that LV outflow tract obstruction decreased from (80 ± 35.5) mm Hg in the TASH group to (49.3 ± 37.7) mm Hg in the pacemaker group.

AUTHORS' CONCLUSIONS

Trials published to date lack information on clinically relevant end-points. Existing data is derived from small trials at high risk of bias, which concentrate on physiological measures. Their results are inconclusive. Further large and high quality trials with more appropriate outcomes are warranted.

Anesthetic Considerations in the Patient With Valvular Heart Disease Undergoing Noncardiac Surgery

Valvular heart disease can be an important finding in patients presenting for noncardiac surgery. Valvular heart disease and resulting comorbidity, such as heart failure or atrial fibrillation, significantly increase the risk for perioperative adverse events. Appropriate preoperative assessment, adequate perioperative monitoring, and early intervention, should hemodynamic disturbances occur, may help prevent adverse events and improve patient outcome. This review article aims to guide the practitioner in the various aspects of anesthetic management in the perioperative care of patients with valvular heart disease. The pharmacological approach to optimization of patient outcome with drugs, such as βblockers and lipid-lowering medications (statins), is an evolving field, and recent developments are discussed in this article.

Comparison of percutaneous transluminal septal myocardial ablation versus septal myectomy for the treatment of patients with hypertrophic obstructive cardiomyopathy—A meta analysis

BACKGROUND

The effects of percutaneous transluminal septal myocardial ablation (PTSMA) with septal myectomy in patients with hypertrophic obstructive cardiomyopathy (HOCM) are not thoroughly compared.

METHODS

Three articles comparing the effects of PTSMA and septal myectomy treatment for HOCM were identified from a search in Pubmed, and a meta analysis was conducted.

RESULTS

177 patients (86 underwent PTSMA and 91 underwent septal myectomy) were included. Interventricular septum thickness was decreased from 22.1 to 15.1 mm (p<0.05) in PTSMA group and from 22.0 to 13.9 mm (p<0.05) in septal myectomy group; left ventricular end-diastolic dimension was increased from 41.8 to 45.2 mm (p<0.05) in PTSMA group and from 41.8 to 43.9 mm (p<0.05) in septal myectomy group; NYHA class was improved from 3.17 to 1.47 (p<0.05) in PTSMA group and from 2.97 to 1.36 (p<0.05) in septal myectomy group; there were no differences in the two groups. However, left ventricular outflow tract gradient was decreased from 76.0 to 15.7 mm Hg (p<0.05) in PTSMA group and from 74.7 to 9.4 mm Hg (p<0.05) in septal myectomy group and the effect of septal myectomy was better than PTSMA (p<0.05).

CONCLUSIONS

The effects of septal myectomy treatment for HOCM are better with regard to relief of LVOT gradient, and lower risk of pacemaker requirement, compared to PTSMA. Large randomized clinical trials further comparing the two treatments are suggested.

Miocardiopatía hipertrófica en el adulto. Curso clínico y factores pronósticos de 119 pacientes

BACKGROUND AND OBJECTIVE

The purpose of this study was to characterize adult patients with hypertrophic cardiomyopathy (HCM), to compare their mortality with that of the general population and to establish a prognosis based on clinical and noninvasive techniques.

PATIENTS AND METHOD

One hundred nineteen consecutive patients (60 women, mean: 52 [12] years) with HCM were prospectively studied by ECG, Holter, echo-Doppler, exercise testing, myocardial perfusion SPET and radionuclide ventriculography. Prognostic variables included clinical data and parameters derived from these noninvasive techniques.

RESULTS

During a mean follow-up of 10 [6.7] years, 7 patients (5.8%) died of cardiovascular causes (4 cardiac failure and 3 sudden death). The annual mortality rate was 0.6% and the actuarial survival curve for patients with HCM was significantly worse compared with the expected survival curve derived from the general population after adjustment for age and sex (p = 0.008). The presence of atrial fibrillation (p = 0.04), moderate or severe mitral regurgitation (p = 0.02), dynamic gradient > 50 mmHg (p = 0.02), left atrial diameter > 45 mm (p = 0.02), and interventricular septal thickness > 25 mm (p = 0.04) were all predictive of mortality.

CONCLUSIONS

The mortality rate of adult patients with HCM is significantly higher than that expected for the general population and heart failure and sudden death are almost evenly distributed as a cause of death in these patients. Atrial fibrillation, magnitude of mitral regurgitation, dynamic gradient, left atrial dilatation and interventricular septal thickness are the main predictors of death.

Efficacy of implantable cardioverter defibrillator therapy for primary and secondary prevention of sudden cardiac death in hypertrophic cardiomyopathy

Risk stratification and effectiveness of implantable cardioverter-defibrillator (ICD) therapy are unresolved issues in hypertrophic cardiomyopathy (HCM), a cardiac disease that is associated with arrhythmias and sudden death. We assessed ICD therapy in 132 patients with HCM: age at implantation was 34 +/- 17 years, and 44 (33%) patients were aged </= 20 years. Indications were sustained ventricular tachycardia (VT) or cardiac arrest (secondary prevention) in 47 (36%) patients, and clinical features associated with increased risk for sudden death (primary prevention) in 85 (64%) patients. There were 6 deaths and 55 appropriate interventions in 27 (20%) patients during a mean follow-up period of 4.8 +/- 4.2 years: 5-year survival and event-free rates were 96%+/- 2%and 75%+/- 5%, respectively. ICD intervention-free rates were significantly less for secondary than for primary prevention:64%+/- 7%versus 84%+/- 6%at 5 years,P = 0.02. Notably, 59 of 67 events (cardiac arrest and therapeutic ICD interventions), or 88%, occurred during sedentary or noncompetitive activity. Incidence of therapeutic shocks was related to age but not to other reported risk factors, including severity of cardiac hypertrophy, nonsustained VT during Holter monitoring, and abnormal blood pressure response to exercise. ICD related complications occurred in 38 (29%) patients, including 60 inappropriate ICD interventions in 30 (23%) patients. However, 8 (27%) of the patients with inappropriate shocks also had therapeutic interventions. ICD is effective for secondary prevention of sudden death in HCM. However, selection of patients for primary prevention of sudden death, and prevention of device related complications require further refinement.