[Exercise test after acute myocardial infarction: on medical therapy?]. / Test da sforzo nel postinfarto: con terapia?

Given the great relevance of beta-blockers after myocardial infarction, we focused our attention on this therapy, considering also the difficulty of its management: it takes a long time to up titrate as well as to wash out. Other anti-ischemic therapies, i.e. nitroderivatives and calcium-antagonists, are easier to manage and there is less need of precise schedules. Our belief is that predischarge exercise testing should be performed on beta-blocker therapy, since we deem unadvisable to interrupt this treatment in the early phase of the postinfarction clinical course, and the reasons are detailed in the text. After myocardial infarction, beta-blockers may reduce the sensitivity of predischarge exercise testing for the diagnosis of inducible ischemia; however, their interference does not seem to affect negatively the prognostic stratification of the test, also in the "thrombolytic era". This may be true since beta-blockers hide, but also cure, those forms of inducible ischemia of lower clinical importance, and only inducible ischemia occurring in spite of such therapy might be dangerous and should be treated with myocardial revascularization. Patients receiving thrombolytic treatment are a selected minority at lower clinical risk; it is necessary to emphasize that predischarge exercise testing is more frequently positive in these patients, probably because of the presence of residual stenosis of the infarct-related vessel that may often have a trivial relevance. The test has a lower negative predictive value in these patients, mainly for the higher incidence of reinfarction and ischemic events related to plaque instability, events that none of the provocative tests can predict accurately.

Magnitude of left ventricular hypertrophy and risk of sudden death in hypertrophic cardiomyopathy.

BACKGROUND: Sudden death is known to be a possible consequence of hypertrophic cardiomyopathy. Quantification of the risk of sudden death, however, remains imprecise for most patients with this disease. METHODS: We assessed the relation between the magnitude of left ventricular hypertrophy and mortality in 480 consecutive patients with hypertrophic cardiomyopathy. The patients were categorized into five subgroups according to maximal wall thickness: 15 mm or less, 16 to 19 mm, 20 to 24 mm, 25 to 29 mm, and 30 mm or more. Their ages ranged from 1 to 89 years (median, 47). RESULTS: Over a mean follow-up period of 6.5 years, 65 of the 480 patients (14 percent) died: 23 suddenly, 15 of heart failure, and 27 of noncardiac causes or stroke. The risk of sudden death increased progressively and in direct relation to wall thickness (P=0.001), ranging from 0 per 1000 person-years (95 percent confidence interval, 0 to 14.4) for a wall thickness of 15 mm or less to 18.2 per 1000 person-years (95 percent confidence interval, 7.3 to 37.6) for a wall thickness of 30 mm or more and almost doubling from each wall-thickness subgroup to the next. The cumulative risk 20 years after the initial evaluation was close to zero for patients with a wall thickness of 19 mm or less but almost 40 percent for wall thicknesses of 30 mm or more. As compared with the other subgroups, patients with extreme hypertrophy were the youngest (mean age, 31 years), and most (41 of 43) had mild symptoms or no symptoms; of the 12 patients who were less than 18 years old at the initial evaluation, 5 died suddenly. CONCLUSIONS: In hypertrophic cardiomyopathy, the magnitude of hypertrophy is directly related to the risk of sudden death and is a strong and independent predictor of prognosis. Young patients with extreme hypertrophy, even those with few or no symptoms, appear to be at substantial long-term risk and deserve consideration for interventions to prevent sudden death. The majority of patients with mild hypertrophy are at low risk and can be reassured regarding their prognosis.