Patients with hypertrophic cardiomyopathy (HCM) who are treated invasively have an overall survival advantage compared with conservatively treated patients, with the latter group more likely to die from non-cardiac causes, according to a single-center retrospective study published Nov. 29 in the Journal of the American College of Cardiology. However, HCM-related mortality is similar, regardless of a conservative versus invasive strategy.
In patients with resting obstructive HCM, clinical benefit can be achieved after invasive septal reduction therapy. Yet, the study authors noted that it “remains controversial” whether invasive treatment improves long-term survival.
Thus, Warren Ball, MD, from the division of cardiology at Toronto General Hospital, University Health Network in Toronto, Ontario, and colleagues sought to compare the survival of patients with HCM and resting left ventricular outflow tract obstruction managed with an invasive versus a conservative strategy.
The researchers studied a consecutive cohort of 649 patients with resting obstructive HCM. Total and HCM-related mortality were compared in 246 patients who were conservatively managed with 403 patients who were invasively managed by surgical myectomy, septal ethanol ablation or dual-chamber pacing.
Using a multivariable analyses with invasive therapy treated as a time-dependent covariate, the researchers reported that an invasive intervention was a significant determinant of overall mortality.
Overall survival rates were greater in the invasive arm: 99.2 percent at one year, 95.7 percent at five years and 87.8 percent at 10 years. Comparatively, survival rates in the conservative treated group were 97.3 percent at one year, 91.1 percent at five years and 75.8 percent at 10 years.
However, invasive therapy was not found to be a significant independent predictor of HCM-related mortality. The HCM-related survival was 99.5 percent (one year), 96.3 percent (five years) and 90.2 percent (10 years) in the invasive cohort, and 97.8 percent (one year), 94.6 percent (five years) and 86.9 percent (10 years) in the conservative cohort.
These outcomes between the conservative and invasive groups, according to the study authors, remained consistent in two additional circumstances: when they excluded the dual-chamber pacing group; and when they considered the myectomy cohort alone in the invasive group (and excluded both the septal ethanol ablation and pacing groups). However, they noted that patients in the conservative group were significantly older and sicker, with nearly one-fifth of patients in the conservatively treated patients having a major comorbidity.
“A greater proportion of the conservative group died from non-cardiac causes,” they wrote. “However, mildly symptomatic (NYHA functional Class I/II) conservatively managed patients had survival similar to patients managed invasively.”
When referring to the clinical implications of their findings, Ball and colleagues listed three:
- The long-term survival of patients with conservatively treated obstructive HCM is “much better than described in other studies.”
- The results suggest that “symptom control and excellent HCM-related survival can be achieved with medical therapy.”
- The results demonstrate that medically treated class I/II patients with obstructive HCM have similar overall and HCM-related survival to patients treated invasively.