Cardiophile MD

Implantable cardioverter defibrillators (ICD) are life saving devices used for treatment of life threatening ventricular arrhythmias and averting sudden cardiac death.

Some of the rare adverse events which can occur with ICDs are as follows:

Pericardial effusion
Generator pocket hematoma
Lead problems like insulation failure and fracture requiring lead revision
Infection, device pocket erosion
Inappropriate defibrillator discharge (inappropriate shocks), which could be due to T-wave oversensing, lead problems or supraventricular arrhythmias
Some may develop psychological problems due to undue fear for shocks

Functional mitral regurgitation (FMR) occurs due to non-coaptation of mitral leaflets in the setting of left ventricular dilatation. It can occur in cardiomyopathies of both ischemic and idiopathic varieties as well as in left ventricular dilatation due to aortic regurgitation. The distorted shape of the left ventricles restricts the mitral valve closure. Left ventricular remodeling is largely responsible for functional mitral regurgitation. There is increased sphericity of the left ventricle with longer tethering distance and enlarged mitral annulus. But the incidence of functional mitral regurgitation is less than what is expected from left ventricular remodeling. This is thought to be due to the enlargement of mitral leaflets in response to changes in left ventricular enlargement and change in morphology. Enlargement of mitral leaflets may not be due to stretch alone, but also due to active growth of cells and matrix. The enlargement of mitral leaflets causing a less than expect rate of functional mitral regurgitation is more likely to occur in slowly progressive left ventricular dilatation as in chronic aortic regurgitation. For this reason, the chance of functional mitral regurgitation is less in chronic aortic regurgitation than in other cases with corresponding severity of left ventricular dilatation [Beaudoin J et al, J Am Coll Cardiol. 2013;61:1809-1809].

90.7% freedom from recurrent severe mitral regurgitation was documented at twenty years after mitral valve repair in a study by David TE et al [Late outcomes of mitral valve repair for mitral regurgitation due to degenerative disease. Circulation. 2013;127:1485-1492]. They had prospectively followed up eight hundred and forty patients who underwent mitral valve repair for mitral valve regurgitation due to degenerative disease fro 1985 to 2004. Age, functional class and left ventricular ejection fraction predicted late cardiac mortality and valve related mortality. In those in functional class IV at the time of surgery, mitral valve repair failed to normalize the life span. The probability of reoperation at twenty years was around six percent. Freedom from moderate or severe mitral regurgitation was around seventy percent. Predictors of recurrent mitral regurgitation were age, isolated prolapse of anterior mitral leaflet and the severity of myxomatous degeneration in the mitral valve. Longer duration of cardiopulmonary bypass time was also associated with higher risk of recurrent mitral regurgitation. The chance of recurrent mitral regurgitation was reduced by mitral annuloplasty.

Radiation associated heart disease is more noted in survivors of breast cancer and Hodgkin’s disease who had undergone radiotherapy with incidental radiation to the heart. The risk is higher in those who received chemotherapy with agents like anthracyclines in addition to radiation. The features of radiation-associated heart disease could involve all the three layers of the heart with pericarditis, myocardial fibrosis or dysfunction, and valvular damage. Radiation is one of the few conditions, which can cause co-existence of restrictive heart disease with constrictive pericarditis. The conduction system of the heart can also be involved in radiation-associated heart disease. Higher doses and younger age at therapy as well as longer follow up will increase the cumulative incidence of radiation-associated heart disease. Advances in radiotherapy techniques can certainly reduce the dose and volume of exposure to the heart and help in lowering the risk of radiation-associated heart disease.

Mandawat A and colleagues [Safety of Pacemaker Implantation in Nonagenarians. An Analysis of the Healthcare Cost and Utilization Project-Nationwide Inpatient Sample. Circulation. 2013;127:1453-1465.] retrospectively analyzed the data of over one lakh patients aged more than seventy years who had undergone initial pacemaker implantation between 2004 and 2008. Eleven percent of them were nonagenarians (ninety or more years of age). Compared to septuagenarians (70 – 79 years) nonagenarians were more likely to have moderate or severe comorbidities and more likely to be admitted on an emergency basis. While unadjusted mortality and complication rates in septuagenarians were 0.6% and 5.61%, it was 1.87% and 6.31% in nonagenarians. But multivariable analysis revealed that severe comorbidity was a greater predictor of mortality than increasing age. There was also similar association between severe comorbidity and complications. The authors concluded that even though older age predicts poorer outcome, the absolute rates are modest even in nonagenarians and the stronger predictor of poor outcome was comorbidity rather than age.

J. Matthew Brennan and associates from Duke Clinical Research Institute [Long-Term Safety and Effectiveness of Mechanical versus Biologic Aortic Valve Prostheses in Older Patients: Results from the Society of Thoracic Surgeons (STS) Adult Cardiac Surgery National Database. CIRCULATION. Published online before print March 28, 2013,] studied the Society of Thoracic Surgeons Adult Cardiac Surgery Database for those between sixty five and eighty years who underwent aortic valve replacement at six hundred and five centres in the nineteen nineties. There were over twenty four thousand who had undergone biopresthetic implant while there a little less than fifteen thousand had a mechanical prosthesis. Both groups had similar age adjusted risk of death while the risk of reoperation and endocarditis was higher with the bioprosthetics. At the same time, the risk of stroke and bleeding were lower in those with bioprosthetic valves than mechanical valves.

A large randomized clinical trial involving over four thousand seven hundred patients from seventy nine centres across nineteen countries has been published in NEJM [Lamy A et al. Effects of Off-Pump and On-Pump Coronary-Artery Bypass Grafting at 1 Year. N Engl J Med 2013; 368:1179-1188]. One year after coronary artery bypass grafting, there was no significant difference between on pump and off pump bypass surgery in the rate of repeat revascularisation, quality of life or neurocognitive function. The same group had reported earlier that there was no significant difference in the composite outcome of myocardial infarction, death, stroke and new onset renal failure requiring dialysis support.