Ethanol for HOCM
Abstract & Commentary
Synopsis: Septal infarction by intracoronary ethanol injection is beneficial for symptomatic hypertrophic obstructive cardiomyopathy patients refractory to pharmacologic therapy.
Source: Lakkis NM, et al. J Am Coll Cardiol 2000; 36:852-855.
Early reports on the benefits of ethanol injection into septal perforator arteries of patients with hypertrophic obstructive cardiomyopathy (HOCM) were encouraging. Thus, the report of Lakkis and colleagues of the one-year follow-up of their first 50 patients treated is of interest. All their patients were refractory to medical therapy with persistent dyspnea and a resting gradient greater than 40 mm Hg, or a dobutamine (5-20 mg/kg/min) gradient greater than 60 mm Hg due to asymmetric septal hypertrophy and systolic anterior motion of the anterior leaflet of the mitral valve. The procedure consisted of identifying the septal arteries supplying the septal bulge by contrast echocardiography, followed by 2-5 mL of ethanol to fill the vessel. All septal branches were injected until the resting gradient was less than 20 mm Hg. All patients had pacemaker backup either temporary or permanent and were observed in the CCU for 24 hours. In 7/50 patients, the procedure was redone and mean hospital stay was three days. The mean number of arteries injected was 1.7 and all patients expe-rienced chest pain and rises in creatine kinase. NYHA class III or IV symptoms were present in 90% of the patients before treatment and all were class I-II at one year. Also, mean exercise treadmill times increased from 271 to 407 seconds at one year (P = 0.02). Mean resting gradients decreased from 74 to 6 mm Hg at one year (P < 0.001), and dobutamine gradients from 84 to 30 mm Hg. On echo-ejection fraction was unchanged, septal thickness decreased from 2.1 cm to 1.5 cm (P < 0.001) and mitral regurgitation decreased from mild-moderate to zero-trivial (P < 0.01). There were two deaths; one died of a dissected left main coronary artery despite emergency bypass surgery and one died suddenly 10 days after the procedure. Complete heart block requiring a pacemaker developed in 11 patients; 20 had new right bundle branch block; 14 had right bundle plus left anterior hemiblock; and six had left bundle branch block. Lakkis et al concluded that septal infarction by intracoronary ethanol injection is beneficial for symptomatic HOCM patients refractory to pharmacologic therapy.
Comment by Michael H. Crawford, MD
Several more aggressive therapies exist for HOCM patients who remain systematic on beta blockers and calcium antagonists. The least aggressive is dual chamber pacing adjusted to reduce the outflow gradient and increase cardiac output. The most aggressive are surgical septal myectomy and mitral valve replacement. Since the results of septal infarction in this report are better than those reported with pacing and equivalent to the results of myectomy or valve replacement without the risks of surgery, should septal infarction be the preferred treatment?
There are some caveats to septal infarction therapy. First, there were two early deaths, which represent a 4% periprocedure mortality and one late death at 22 weeks. Second, the procedure was painful despite premedication with narcotics and resulted in several days of hospitalization. Third, according to the text, all of the 50 patients developed conduction abnormalities or already had a pacemaker and 11 required a new permanent pacemaker. Given these complications, it would seem reasonable to try dual chamber pacing first in drug refractory HOCM patients and consider ethanol septal infarction for those that fail pacing therapy
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